In this appeal, we consider whether a municipality's assessor may apply a uniform adjustment factor to a neighborhood's appraised property values during the mass appraisal process for the revaluation of real property pursuant to General Statutes § 12-62 (b), 1 as a direct equalization measure in order to ensure that neighborhood is not undertaxed relative to others in the municipality. The plaintiffs, John P. Tuohy and numerous other owners of real property located in the Groton Long Point neighborhood, 2 brought this class action tax appeal pursuant to General Statutes § 12-119 3 against the defendants, the town of Groton (town) and Mary Gardner, its assessor, challenging the assessed value of their properties following the revaluation conducted by the town for its October 1, 2011 grand list (2011 revaluation). The plaintiffs now appeal 4 from the judgment in favor of the defendants, rendered after a trial to the court, upholding the legality of those assessments. On appeal, the plaintiffs claim that the trial court incorrectly determined that their assessments were not manifestly excessive because the defendants violated § 12-62 and numerous provisions of the Regulations of Connecticut State Agencies (regulations) promulgated by the state Office of Policy and Management (OPM); see Regs., Conn. State Agencies § 12-62i-1 et seq. ; when they applied a flat, undifferentiated adjustment factor that increased the assessed value of all properties in Groton Long Point by 35 percent without individualized consideration of the unique characteristics of each property. We conclude that the defendants properly applied an adjustment factor as a direct equalization measure in connection with an assessment to sales ratio study conducted pursuant to various standards promulgated by the International Association of Assessing Officers (international association) in order to ensure that Groton Long Point bore its fair share of the town's municipal tax burden relative to the town's other neighborhoods. Accordingly, we affirm the judgment of the trial court.

The record reveals the following facts, as comprehensively found by the trial court, Moll, J. , 5 and procedural history. "The plaintiffs are residential property owners in the Groton Long Point ... neighborhood 6 of [the town], who, on behalf of themselves and the certified class, 7 are challenging the [2011 revaluation]. [Groton Long Point] is a planned community and comprises approximately 600 properties. When someone owns property in [Groton Long Point], he or she pays into an association and has rights to use certain amenities within the community, including the beach, docks, piers, and association buildings, which include, among other things, a restaurant. In addition, parking in [Groton Long Point] requires a permit.

"The 2011 revaluation was a mass appraisal, defined as 'the process of valuing a universe of properties as of a given date using standard methodology, employing common data, and allowing for statistical testing. Methodology that is acceptable shall include, but is not limited to, automated valuation models, adaptive estimation procedure, multiple regression analysis, statistical analysis and other generally accepted techniques ....' Regs., Conn. State Agencies § 12-62i-1 (10). The 2011 revaluation was overseen by ... Gardner ... whose position as the town assessor began in June, 2011. Gardner first worked in the town's assessor office in 1986; she became a certified assessor in 1989. The 2011 revaluation was the first revaluation that Gardner conducted as an assessor.

"To assist it with the 2011 revaluation, the town hired Tyler Technologies (Tyler), a mass appraisal vendor certified by the state to do revaluations. [See General Statutes § 12-62 (e) ]. The project supervisor from Tyler with respect to the 2011 revaluation was Debra Christy ... who also is certified to do revaluations. Christy has been employed with Tyler, although not continuously, since 1980 and has been involved with revaluations in the state of Connecticut since around 1997. Christy had some responsibility in the 2006 revaluation of Groton but was not the manager. In the 2011 revaluation, Christy was responsible for the analysis for the residential property class.

"The 2011 revaluation commenced in earnest in April, 2010, at which time Gardner was the assistant assessor for the town. In April, 2010, the town issued a press release informing the public that a revaluation would be underway and that data collectors would be going door to door to measure the exteriors of all properties and to attempt interior inspection, if allowed. Tyler conducted its data collection using data from the 2006 revaluation and updating it. Because the 2011 revaluation was a full measure revaluation, Tyler [employees] knocked on every door and did an exterior measurement of every property. To the extent access to the interior was not granted, Tyler sent the property owner a callback letter to inquire whether the owner would make a scheduled appointment for an interior inspection. Tyler then prepared and distributed data mailers for each property; such data mailers reflected the property's physical characteristics that would be used in the revaluation. Property owners were asked to contact Tyler if any information required correction. Any changes resulting from the data mailer process were inputted into the Computer Assisted Mass Appraisal (CAMA) software system, which the town uses for its revaluations to generate property values. CAMA is certified by the state of Connecticut and is an example of an 'automated valuation model,' as that phrase is used in § 12-62i-1 (10) [of the regulations], which sets forth the definition of '[m]ass appraisal.' In CAMA, with respect to each property, a value is assigned to the land, 8 and a value is assigned to any improvements or structures using the cost approach (i.e., the cost of replacement with an adjustment for depreciation). The improvements value comprises a dwelling value and an outbuilding value. One arrives at total value by adding land value and improvements value.

"Tyler then performed a prereview, which involved producing all of the property record cards that were in the system and having a certified field person go out to each property to conduct what Tyler called a 'wind-shield prereview check' to ensure that the information on the cards was accurate.

"After all data were collected and corrected during the eighteen-month period following the initial press release, Tyler engaged in preliminary ratio testing, which required compiling a validated sales set (i.e., sales involving actual warranty deeds) using a two year lookback period because of the number of sales. 9 With respect to [Groton Long Point], the sales set contained eighteen validated, arm's-length transactions. Tyler compared the median of the sales identified for each neighborhood against the median for the total value for the neighborhood. A 1:1 ratio, meaning the medians are equal, would be considered ideal. Tyler performed preliminary ratio testing for each of the thirteen neighborhoods within the town. 10 The same process was followed in 2006.

"On October 31 and November 1, 2011, Christy conducted four computer runs to create values for the [Groton Long Point] residential properties using the CAMA software. The 2006 revaluation had used an adjustment factor of 1.2 (i.e., a 20 percent increase in value) in setting the improvement values of the [Groton Long Point] properties. Those adjustments were already reflected in the CAMA database that Christy used in conducting her analyses. Because an adjustment factor of 1.2 was used in 2006 with respect to [Groton Long Point] improvement values, Christy used that adjustment factor as a starting point. Application of an adjustment factor of 1.2 yielded a median assessment to sales ratio (ASR) 11 of 88.31 percent for [Groton Long Point]. Christy found this ratio to be outside an acceptable range because it fell under 90 percent. 12 In this regard, Tyler and the town deemed [Groton Long Point] to be an outlier. Specifically, in reaching this conclusion, Christy relied on the [international association's] 13 principle that, when looking at the level of assessment, if market value is 100 percent, the [median] ASR should be plus or minus 10 percent around market value. Applying an adjustment factor of 1.4 yielded a median ASR of 95.08 percent. Applying an adjustment factor of 1.4 with a waterfront adjustment yielded a median ASR of 97.56 percent. Finally, application of an adjustment factor of 1.35 yielded a median ASR of 92.03 percent.

"Tyler and the town concluded that applying an adjustment factor of 1.35 to the dwelling values within [Groton Long Point] was appropriate and necessary to reach fair market value. Christy reasoned that other variables, including a coefficient of dispersion, fell within a preferred range to reach uniformity. [Tyler did not physically reinspect any of the Groton Long Point properties prior to applying the 1.35 adjustment factor.] 14

"Christy conducted sales ratio studies with respect to each of the other twelve neighborhoods. Using a 1.0 factor, each neighborhood's median ASR landed above 90 percent (and below 100 percent market value). For each of the other neighborhoods, the resulting median ASRs were as follows:

1010-Center Groton 91.80 percent

1020-City of Groton 92.99 percent

1021-City of Groton-Eastern 96.43 percent

1030-Poquonock Bridge 96.28 percent

1040-Mystic 94.10 percent

1041-Mystic Village 94.37 percent

1050-Noank 95.08 percent

1051-Noank Village 94.69 percent

1060-Old Mystic 96.46 percent

1061-Old Mystic-River Road 95.14 percent

1080-West Pleasant Valley 95.73 percent

1090-Mumford Cove 94.78 percent

Because these median ASRs fell above 90 percent, and therefore were deemed acceptable, no adjustments were made.

"Thereafter, Tyler entered into what it called the final review phase. Because the town had elected to use ratio testing standards, and not procedural testing standards, Christy conducted ratio testing to residential property townwide to assure satisfaction of the requirements of § 12-62i-3 (b) [of the regulations]. Such testing to such property class on a townwide basis resulted in those criteria being met on the first try. Therefore, no further analysis was performed pursuant to § 12-62i-3 (c). The town subsequently submitted to [OPM] the statutorily required certification of compliance, which was signed by Christy and Gardner and which reflected that the town utilized ratio testing standards." 15 (Footnotes added and in original.)

The plaintiffs subsequently brought this class action pursuant to § 12-119, seeking reduction of the assessments on the relevant properties in Groton Long Point. The plaintiffs claimed, inter alia, that the "uniform application of the 1.35 adjustment factor to residential buildings" violated § 12-119 because (1) "the application of a fixed percentage factor to increase assessments without making any allowance for individual differences in properties has been widely condemned by the courts of this state," (2) "the basic deficiency of such a valuation procedure is the failure to consider all of the elements which may reasonably affect the value of the property," (3) "the assumption that residential buildings in Groton Long Point are worth 35 percent more than comparable structures elsewhere in the town, including but not limited to structures in the sections of town classified as Mumford Cove, Mystic Village, and Noank Village, is arbitrary, unreasonable, and without foundation in fact," and (4) "the application of the fixed percentage factor by the assessor to increase the assessments on properties in Groton Long Point cannot reasonably be found to fulfill her statutory duty to determine the true and actual valuation of each individual property, in violation of [General Statutes] § 12-64...."

Following certification of the class; see footnote 7 of this opinion; the case was tried to the court. 16 After conducting a comprehensive review of the governing statutory and regulatory framework, and particularly the ratio testing standard set forth in § 12-62i-3 of the regulations 17 for evaluating the performance of the revaluation process, the trial court concluded that the "1.35 adjustment factor applied to the [Groton Long Point] dwelling values did not violate § 12-119." In so concluding, the trial court rejected the plaintiffs' argument that the defendants had disregarded a legal duty insofar as the ratio testing standards may be applied only on a townwide basis, rather than to specific neighborhoods on a preliminary basis. The trial court also rejected the plaintiffs' reliance on Chamber of Commerce of Greater Waterbury, Inc. v. Waterbury , 184 Conn. 333 , 439 A.2d 1047 (1981), for the "proposition that, in the revaluation context, the application of a fixed percentage without allowance for individual property differences is illegal pursuant to § 12-119"; the court distinguished that case factually with respect to the extensive, individualized data collection that took place in the present case. To this end, the trial court concluded that Tyler was not required to "physically [re]inspect the [Groton Long Point] residential properties" after it discovered that the initial "application of the original 1.2 adjustment factor yielded a median ASR of 88.31 percent ...." 18 Having credited the testimony of Gardner and Christy to the effect that the 1.35 adjustment factor "was used for the express purpose of increasing the [Groton Long Point] appraised values so that they would be closer to fair market value, instead of well below fair market value," the trial court rejected the plaintiffs' claim that "their assessments were manifestly excessive" and the "illegal" result of "disregard of the relevant statutes ...." Accordingly, the trial court rendered judgment for the defendants. This appeal followed.

On appeal, the plaintiffs claim that the trial court incorrectly concluded that the defendants' assessment of Groton Long Point in the 2011 revaluation was not illegal. The plaintiffs renew their reliance on Chamber of Commerce of Greater Waterbury, Inc. , and contend that the defendants' use of an undifferentiated adjustment factor of 1.35 disregarded the "individualized process" required by § 12-62, insofar as "[t]here is no provision in our state statutes or the pertinent regulations that allows an assessor to apply a flat percentage to a group of properties simultaneously in order to 'adjust' their true and actual value." The plaintiffs further argue that the defendants' use of the adjustment factor was not authorized by § 12-62i-3 of the regulations, which contemplates the use of ratio testing for property classes, namely, residential, commercial, and vacant land, rather than "on much smaller groups, i.e., residential neighborhoods," and only to verify results, not "to actually set the assessed values themselves." The plaintiffs contend that any discrepancy resulting from the initial mass appraisal should have been addressed by "physically revisit[ing] those properties [to] verify the data collection and the information it produced," rather than arbitrarily "running calculations until the numbers (subjectively) seem to more closely approximate some ideal of fair market value in the assessor's mind ...." 19 Finally, the plaintiffs rely on Hartford/Windsor Healthcare Properties, LLC v. Hartford , 298 Conn. 191 , 3 A.3d 56 (2010), and argue that the trial court improperly found that they had "failed to demonstrate that the 2011 [revaluation] resulted in assessments that are manifestly excessive," because that determination is "part and parcel of the stipulation that the defendants uniformly inflated the assessed value of the subject properties by 35 percent even though such an adjustment was not required in order to comply with the statutory standards."

In response, the defendants contend that they properly utilized the 1.35 adjustment factor to compensate for patterns of undervaluation of Groton Long Point properties relative to other neighborhoods in the town.

The defendants argue that this methodology was consistent with the OPM regulations and the standards of the international association, and emphasize that OPM itself ultimately certified the results of the appraisal. Thus, the defendants also rely on Redding Life Care, LLC v. Redding , 308 Conn. 87 , 61 A.3d 461 (2013), and contend that the plaintiffs have failed to prove a violation of § 12-119 because their complaint of "inadequate substantiation to support application of the 1.35 adjustment factor" pertains to insufficiency of data and a challenge to the appraisal methodology, rather than demonstrating illegality. The defendants further argue that Chamber of Commerce of Greater Waterbury, Inc. v. Waterbury , supra, 184 Conn. at 333 , 439 A.2d 1047 , is distinguishable from the present case because, in addition to engaging in a comprehensive preappraisal field data gathering as to every property in town, Tyler reanalyzed that field data subsequent to the adjustment to verify the consistency of the mass appraisal results with actual property values as determined by sales. Finally, the defendants contend that the plaintiffs failed to prove that the valuation of their properties was manifestly excessive because they did not present any credible evidence of the values of their properties. We agree with the defendants and conclude that their application of the 1.35 adjustment factor to the Groton Long Point residential properties during the 2011 revaluation was not illegal.

"In a tax appeal taken pursuant to § 12-119, the plaintiff must prove that the assessment was (a) manifestly excessive and (b) ... could not have been arrived at except by disregarding the provisions of the statutes for determining the valuation of the property.... [The plaintiff] must [set forth] allegations beyond the mere claim that the assessor overvalued the property. [The] plaintiff ... must satisfy the trier that [a] far more exacting test has been met: either there was misfeasance or nonfeasance by the taxing authorities, or the assessment was arbitrary or so excessive or discriminatory as in itself to show a disregard of duty on their part.... Only if the plaintiff is able to meet this exacting test by establishing that the action of the assessors would result in illegality can the plaintiff prevail in an action under § 12-119. The focus of § 12-119 is whether the assessment is illegal.... The statute applies only to an assessment that establishes a disregard of duty by the assessors....

"While an insufficiency of data or the selection of an inappropriate method of appraisal could serve as the basis for not crediting the appraisal report that resulted, it could not, absent evidence of misfeasance or malfeasance , serve as the basis for an application for relief from a wrongful assessment under § 12-119.... In short, when reviewing a claim raised under § 12-119, a court must determine whether the plaintiff has proven that the assessment was the result of illegal conduct." 20 (Emphasis in original; internal quotation marks omitted.) Walgreen Eastern Co. v. West Hartford , 329 Conn. 484 , 513-14, 187 A.3d 388 (2018). Put differently, tax relief under § 12-119 is available only in an "extraordinary situation." Second Stone Ridge Cooperative Corp. v. Bridgeport , 220 Conn. 335 , 343, 597 A.2d 326 (1991).

Whether an assessment methodology violates the governing statutes and regulations for purposes of § 12-119 presents a question of law over which our review is plenary. See, e.g., Griswold Airport, Inc. v. Madison , 289 Conn. 723 , 739, 961 A.2d 338 (2008) ; see also Redding Life Care, LLC v. Redding , supra, 308 Conn. at 101 , 61 A.3d 461 ("[w]hen a tax appeal ... raises a claim that challenges the propriety of a particular appraisal method in light of a generally applicable rule of law, our review of the trial court's determination whether to apply the rule is plenary" [internal quotation marks omitted] ); Griswold Airport, Inc. v. Madison , supra, at 741-42, 961 A.2d 338 (applying plenary review to claim that assessor violated General Statutes § 12-504h by terminating property's open space classification and assessing it as condominium units).

Our review of the legality of the assessment begins with the OPM regulations, which were promulgated pursuant to § 12-62 (g) ; see footnote 17 of this opinion; for the purpose of guiding the revaluation process under § 12-62 (b) (2), which contemplates both a "field review" of the properties and the use of "generally accepted mass appraisal methods which may include, but need not be limited to, the market sales comparison approach to value, the cost approach to value and the income approach to value." Beyond the regulations, we also consider the extent to which the appraisal complied with the Uniform Standards of Professional Appraisal Practice, as promulgated by the Appraisal Standards Board of the Appraisal Foundation, which "[r]eal estate appraisers in Connecticut are required to follow" pursuant to General Statutes § 20-504. Redding Life Care, LLC v. Redding , supra, 308 Conn. at 107 n.18, 61 A.3d 461 .

Section 12-62 (g) (2) mandates the promulgation of regulations "establishing criteria for measuring the level and uniformity of assessments generated from a revaluation," and provides that "such criteria shall be applicable to different classes of real property with respect to which a sufficient number of property sales exist." The regulations promulgated by OPM in response to that mandate, in turn, provide that "[p]erformance-based revaluation standards shall consist of two acceptable methods as set forth in section[s] 12-62i-3 and 12-62i-4 of the [r]egulations ...." Regs., Conn. State Agencies § 12-62i-2. Ratio testing, one of the two acceptable methods, is governed by § 12-62i-3 of the regulations. That regulation requires an assessor conducting ratio testing to establish "[a] file of all real property sales transactions for the sales time period used"; Id., § 12-62i-3 (a) (1); and also provides that, "[p]rior to finalizing a revaluation, the assessor shall conduct the following tests regarding the assessments derived from such revaluation. The assessments resulting from the revaluation shall be deemed sufficient, provided the following criteria are met:

"(1) the overall level of assessment for all property classes shall be within plus or minus ten percent of the required seventy percent assessment ratio, as measured by the overall median ratio, and

"(2) the level of assessment for each property class with fifteen or more market sales shall be within plus or minus five percent of the median overall level of assessment for each property class, and

"(3) the coefficient of dispersion for each property class with fifteen or more market sales shall be equal to or less than fifteen percent for all property, equal to or less than fifteen percent for residential property, equal to or less than twenty percent for commercial property, and equal to or less than twenty percent for vacant land, and

"(4) the price related differential for all properties and for each property class for which there are fifteen or more market sales shall be within 0.98 and 1.03, and

"(5) the unsold property test result shall be between 0.95 and 1.05." Id., § 12-62i-3 (b).

The ratio testing regulation further provides that, if its criteria "are not met, the assessor shall, prior to the implementation of the revaluation, further analyze and refine the data elements or methods used in the revaluation. The assessor shall revalue the parcels of real property for which a deficiency in either the level of assessment or the uniformity of assessments has been identified." Id., § 12-62i-3 (c).

The plaintiffs correctly read the ratio testing regulation as mandating such evaluation following the completion of the appraisal by general " '[p]roperty class,' " which is defined as "any one of the following three major classifications of real property: (A) residential; (B) commercial including apartments, industrial and public utility; and (C) vacant land ...." Id., § 12-62i-1 (15). There are, however, two problems with the plaintiffs' interpretation of the ratio testing regulation. First, that regulation does not expressly preclude the use of ratio testing or adjustment factors during the mass appraisal process by " '[n]eighborhood,' " which is defined as "a geographic area of complementary real property parcels that share similar locational and market value characteristics, and may be defined by natural, man-made, or political boundaries ...." Id., § 12-62i-1 (13). Reading the ratio testing regulation in the manner urged by the plaintiffs would require us to add nonexistent language to its text, which is not how we read regulations. See, e.g., Williams v. General Nutrition Centers, Inc. , 326 Conn. 651 , 657, 166 A.3d 625 (2017) ("because regulations have the same force and effect as statutes, we interpret both using the plain meaning rule"); Mayer v. Historic District Commission , 325 Conn. 765 , 776, 160 A.3d 333 (2017) ("it is well settled that [w]e are not permitted to supply statutory language that the legislature may have chosen to omit" [internal quotation marks omitted] ).

Second, the plaintiffs' reading of § 12-62i-3 of the regulations is inconsistent with the other regulatory text, which defines " '[r]evaluation' " as "the mass appraisal of property to determine the true and actual value of all real property in a town for assessment purposes in accordance with section 12-62...." Regs., Conn. State Agencies § 12-62i-1 (19). The very meaning of " '[m]ass appraisal' " contemplates some estimation, insofar as it is defined as "the process of valuing a universe of properties as of a given date using standard methodology, employing common data, and allowing for statistical testing. Methodology that is acceptable shall include, but is not limited to, automated valuation models, adaptive estimation procedure, multiple regression analysis, statistical analysis and other generally accepted techniques ...." Id., § 12-62i-1 (10). Indeed, § 12-62f-4 of the regulations, which governs the valuation module to be used for computer assisted mass appraisal, specifically anticipates such testing on a neighborhood basis, as such a valuation module must have "the capacity to calculate, print reports and output to standard analytical software programs the following measurements and sales/assessment ratios by property type and neighborhood : Sales prices; assessments; the mean sales/assessment ratio; the median sales/assessment ratio; the coefficient of dispersion; the standard deviation; the coefficient of variation; and the price-related differential." (Emphasis added.) Id., § 12-62f-4 (d). Thus, to read § 12-62i-3 of the regulations in a manner absolutely precluding ratio testing on a more granular level than property class during the mass appraisal process would make little sense, as that regulation simply furnishes a broad measure of quality control to be implemented "[p]rior to finalizing a revaluation ...." Id., § 12-62i-3 (b).

Beyond the lack of regulatory or statutory preclusion, the Uniform Standards of Professional Appraisal Practice support the defendants' use of a ratio study during the mass appraisal process at issue in the present case. 21 Specifically, rule 6-7 of the Uniform Standards of Professional Appraisal Practice provides that "[i]n reconciling a mass appraisal an appraiser must: (a) reconcile the quality and quantity of data available and analyzed within the approaches used and the applicability and relevance of the approaches, methods and techniques used; and (b) employ recognized mass appraisal testing procedures and techniques to ensure that standards of accuracy are maintained." Appraisal Standards Board, Appraisal Foundation, 2010-11 Uniform Standards of Professional Appraisal Practice (2010) p. U-51. The commentary to that rule observes that "[i]t is implicit in mass appraisal that, even when properly specified and calibrated mass appraisal models are used, some individual value conclusions will not meet standards of reasonableness, consistency, and accuracy. However, appraisers engaged in mass appraisal have a professional responsibility to ensure that, on an overall basis, models produce value conclusions that meet attainable standards of accuracy. This responsibility requires appraisers to evaluate the performance of models, using techniques that may include but are not limited to, goodness-of-fit statistics, and model performance statistics such as appraisal-to-sale ratio studies , evaluation of hold-out samples, or analysis of residuals." (Emphasis added.) Id.; see also id., p. U-53 (noting that written report of mass appraisal must "describe calibration methods considered and chosen," "identify the appraisal performance tests used and set forth the performance measures attained," and "describe the reconciliation performed [under rule] 6-7"). Consistent with the Uniform Standards of Professional Appraisal Practice, the use of ratio studies and "direct equalization" via the application of adjustment factors are an established component of mass appraisal practice, and are specifically embraced by the international association. See generally International Association of Assessing Officers, Standard on Ratio Studies (2013); International Association of Assessing Officers, Fundamentals of Mass Appraisal (2011). 22 The "assessment standards set forth" in the international association's standards "represent a consensus in the assessing profession," and the international association's executive board adopted them in order to "provide a systematic means by which concerned assessing officers can improve and standardize the operation of their offices." Standard on Ratio Studies, supra, p. 1. Those standards have been considered authoritative in this area by sister state high courts. See Douglas v. Nebraska Tax Equalization & Review Commission , 296 Neb. 501 , 508, 894 N.W.2d 308 (2017) ("[g]enerally accepted mass appraisal techniques include the standards promulgated by the [international association]"); Clifton v. Allegheny , 600 Pa. 662 , 694, 969 A.2d 1197 (2009) (noting that international association standards "are widely accepted as the best criteria for judging the adequacy of a property assessment"); see also Thorsness v. Porter County Assessor , 3 N.E.3d 49 , 53 (Ind. Tax 2014) (noting that state "administrative agency charged with ensuring that ... property assessments are uniform and equal-has provided guidance about how to compile and evaluate the data necessary for an assessment ratio study" by adopting international association's standards "through its duly promulgated administrative regulations" [footnote omitted] ). A separate publication by the international association, entitled Fundamentals of Mass Appraisal, complements their standards and serves as a more general "textbook [that] is intended to provide a basic understanding and overview of the many factors that shape mass appraisal theory and practice." Fundamentals of Mass Appraisal, supra, p. v.

Beyond their use in quality control by oversight agencies such as OPM, the international association's standards suggest specifically that ratio studies may be utilized internally to "help improve appraisal methods or identify areas within the jurisdiction that need attention." Standard on Ratio Studies, supra, p. 7. Ratio studies may be used to consider the accuracy of a mass appraisal, including with respect to "[u]niformity" or "the degree to which properties are appraised at equal percentages of market value." 23 Id.; see also id., p. 8 ("Local jurisdictions should use ratio studies as a primary mass appraisal testing procedure and their most important performance analysis tool. The ratio study can assist such jurisdictions in providing fair and equitable assessment of all property."). The "ratio study is a form of applied statistics, because the analyst draws conclusions about the appraisal of the population (the entire jurisdiction) of properties based only on those that have sold during a given time period. The sales ratios constitute the sample that will be used to draw conclusions or inferences about the population." Id., p. 8.

With respect to data collection and analysis, the international association's standards contemplate "[s]tratification [to divide] all the properties within the scope of the study into two or more groups or strata," which "facilitates a more complete and detailed picture of appraisal performance and can enhance sample representativeness." Id., p. 9. In observing that stratification can "help identify differences in level of appraisal between property groups," those standards specifically suggest that "neighborhood" is an appropriate stratum, in addition to "[e]ach type of property subject to a distinct level of assessment," with "stratification by geographic areas ... generally more appropriate for residential properties ...." Id. Once appropriate sales are identified during the collection of market data, the statistical analysis takes place, as those sales are "matched against assessed values, ratios computed, and outliers identified and removed if appropriate, measures of appraisal level, uniformity, and reliability for the entire jurisdiction and each group or stratum should be computed." Id.

The international association allows for a 10 percent "window ... about the market value standard [as] a reasonable range in which measures of central tendency should fall in ad valorem mass appraisal." Fundamentals of Mass Appraisal, supra, p. 243. This "standard provides a reasonable, constructive, and cost-effective basis for ensuring that appraisals approximate market values." Id. With respect to uniformity among the various strata, "[e]ach major stratum should be appraised within 5 percent of the overall level of appraisal for the jurisdiction. Thus, if the overall level is 0.900, each property class and area should be appraised between 0.855 and 0.945 ...." Id.; see also Standard on Ratio Studies, supra, pp. 18-19.

Most significantly, the international association's standards contemplate the "common" use of "[e]qualization ... to address problems associated with appraisal level," while also observing that "[r]eappraisal orders can be used to correct uniformity problems." Standard on Ratio Studies, supra, p. 21. "Equalization," in general, is the "process by which an appropriate governmental body attempts to ensure that property under its jurisdiction is assessed at the same assessment ratio or at the ratio or ratios required by law. Equalization can be undertaken at many different levels. Equalization among use classes (such as agricultural and industrial property) can be undertaken at the local level ...." Id., p. 40. "Direct equalization" 24 is the "process of converting ratio study results into adjustment factors (trends) and changing locally determined appraised or assessed values to more nearly reflect market value or the legally required level of assessment." 25 Id.

Although the international association's standards caution that "[e]qualization is not an appraisal or a substitute for reappraisal," they nevertheless counsel that the advantage of direct equalization is that it "can be applied to specified strata, such as property classes, geographic areas, and political subdivisions that fail to meet appraisal level performance standards .... Direct equalization also produces results that are generally more visible to the taxpayer and more clearly reduces perceived inequities between classes ...." (Citations omitted; emphasis added.) Id., p. 21; see also id., p. 23 ("[o]ther property groups, such as market areas, school districts and tax units, could constitute additional strata"). Indeed, when "applied at the stratum level [direct equalization] improves equality in effective tax rates between strata and lessens the effect of assessment practices that improperly favor one stratum over another." 26 Id., p. 22. Those standards note that "[s]tratification can help identify differences in level of appraisal between property groups. In large jurisdictions, stratification by market areas is generally more appropriate for residential properties, while stratification of commercial properties by either geographic area or property subtypes (e.g., office, retail, and warehouse/ industrial) can be more effective." Id., p. 24. Such "[s]tratification facilitates a more complete and detailed picture of appraisal performance and can enhance sample representativeness." Id., p. 23.

"If noncompliance with either direct or indirect equalization standards is indicated, the appropriate point estimate (statistic) measuring appraisal level should be used to calculate adjustment factors, by dividing it into 100 percent." Id., p. 35. Accordingly, we conclude that the record demonstrates that the use of ratio studies and direct equalization via adjustment factors as applied to a neighborhood stratum is a valid component of mass appraisal practice under the standards adopted by the international association.

Having determined that the defendants validly incorporated ratio studies and direct equalization via adjustment factors to neighborhood strata into the 2011 revaluation, we further conclude that the trial court properly rejected the plaintiffs' challenge to their use in this specific case. The trial court credited Gardner's testimony that the application of the 1.35 percent adjustment factor to the dwellings in Groton Long Point was necessary to bring the median ASR for that neighborhood in line with the other neighborhoods in the town, and to keep the properties in Groton Long Point from being undervalued-and therefore undertaxed-relative to the rest of the town. Gardner testified that stratification by neighborhood was necessary because Groton has thirteen neighborhoods, each "unique to itself," with five on the water and others with "interior cookie cutter homes." Although the amenities available to Groton Long Point residents, such as the private beaches and dock, run with the land, Gardner elected to adjust the building values as a component of the total value, rather than the land values, because she had high confidence in the underlying land values based on a comparison to three valid vacant lot sales. "[T]his court has held that [t]he process of estimating the value of property for taxation is, at best, one of approximation and judgment, and there is a margin for a difference of opinion.... There may be more ways than one for estimating the value of such ... [property] for taxation.... Many factors may enter into the determination of the value of a piece of property. Its value is, in the final analysis, a matter of opinion." (Citation omitted; internal quotation marks omitted.) Redding Life Care, LLC v. Redding , supra, 308 Conn. at 110 , 61 A.3d 461 .

This court's decision in Chamber of Commerce of Greater Waterbury, Inc. v. Waterbury , supra, 184 Conn. at 333 , 439 A.2d 1047 , on which the plaintiffs rely heavily, is distinguishable and does not invalidate the town's 2011 revaluation as a matter of law. In that case, we considered a challenge to Waterbury's revised grand list for October 1, 1979, which "consisted of adjustments made in the assessments of about 300 commercial and industrial properties, which [the assessor] and his staff inspected and analyzed individually, and a 28 percent increase 'across the board' in the assessments of the remaining commercial and industrial properties in Waterbury, approximately 2500 in number." Id., at 334-35, 439 A.2d 1047 . This court affirmed the judgment of the trial court enjoining the fixed 28 percent increase, determining that the "application of a fixed percentage factor to increase assessments without making any allowance for individual differences in properties has been widely condemned.... The basic deficiency of such a valuation procedure is the failure to consider all of the elements which may reasonably affect the value of the property." (Citations omitted.) Id., at 336-37, 439 A.2d 1047 .

In concluding that the fixed 28 percent increase without consideration of the properties' individual characteristics was illegal, this court observed that, under §§ 12-64 (a) and 12-62 (a), "[t]axable property is subject to taxation at a uniform percentage of 'its present true and actual valuation.' ... In establishing assessments the assessors are required to 'view all of the real estate of their respective municipalities.' ... These statutes contemplate assessments based upon a consideration of the individual characteristics of each property listed." (Citations omitted.) Id., at 337, 439 A.2d 1047 . The court concluded that the "28 percent increase in the valuations of the 2500 commercial and industrial properties which [the assessor] did not examine individually was a projection from the conclusion he reached from his analysis of 300 such properties upon an individual basis. His conclusion of a minimum 28 percent undervaluation of those properties could not fairly be applied to all other business properties in Waterbury without some showing that the undervaluation had occurred for reasons affecting all business properties alike. We cannot assume that the 300 properties studied by the assessor are sufficiently similar in character or location to allow a reasonable inference that the remaining 2500 properties have been uniformly undervalued by 28 percent." 27 (Emphasis added.) Id., at 337, 439 A.2d 1047 . Accordingly, the court concluded "that the application of the fixed percentage factor by the assessor to increase the assessments on the properties of the plaintiffs cannot reasonably be found to fulfill his statutory duty to determine the 'true and actual valuation' of each individual property." 28 Id., at 338, 439 A.2d 1047 . Chamber of Commerce of Greater Waterbury, Inc. , is readily distinguishable from the present case. First, the record in the present case reveals that Gardner and the assessment team from Tyler made an individual assessment of every property in the town-including field visits, requests for inspections, and communications with each homeowner prior to the finalization of the assessment in accordance with § 12-62 (b) and § 12-62i-3 of the regulations. The trial court reasonably credited the testimony of Gardner and Christy that additional visits were not necessary prior to the application of the adjustment because they had gained all relevant information about the properties. See footnote 14 of this opinion and accompanying text. Second, in contrast to Chamber of Commerce of Greater Waterbury, Inc. , the adjustment in this case was not applied townwide, but rather, only to a narrow strata of properties in a unique neighborhood in connection with a computer assisted mass appraisal that was conducted in accordance with both the OPM regulations and widely accepted appraisal standards. Accordingly, we conclude that Chamber of Commerce of Greater Waterbury, Inc. , does not render the assessment in the present case illegal. 29 The plaintiffs contend, however, that the application of the 1.35 adjustment factor was invalid because it was arbitrarily chosen by Christy, "had no mathematical or technical connection to the initial assessments made by the CAMA program, and was not intended to remedy some specific defect." They argue that it is "completely unrelated to the true and actual value of each home in Groton Long Point." To this end, the plaintiffs rely on certain data presented through the testimony of Edward Bogdan, a member of the certified class in the present case; see footnote 7 of this opinion; in support of the proposition that Groton Long Point experienced a 25 percent decrease in home sale prices between 2009 and 2011. Specifically, the plaintiffs posit that this information undermines the sales set utilized by Christy in performing her assessments. This evidence is insufficient, however, to establish illegality, insofar as "[w]hile an insufficiency of data or the selection of an inappropriate method of appraisal could serve as the basis for not crediting the appraisal report that resulted, it could not, absent evidence of misfeasance or malfeasance, serve as the basis for an application for relief from a wrongful assessment under § 12-119." Second Stone Ridge Cooperative Corp. v. Bridgeport , supra, 220 Conn. at 343 , 597 A.2d 326 ; see also Redding Life Care, LLC v. Redding , supra, 308 Conn. at 111 , 61 A.3d 461 ("although the plaintiff may disagree that the hypothetical condition was necessary to reach the valuation, it has failed to demonstrate that the town assessor's reliance on the condition was illegal , and, accordingly, the plaintiff cannot prevail on its claim under § 12-119" [emphasis in original] ). Moreover, the plaintiffs have failed to introduce evidence to prove that the adjustment to the appraised value-even by 35 percent-actually resulted in a manifest overvaluation of their properties relative to true and actual fair market value. 30 See Walgreen Eastern Co. v. West Hartford , supra, 329 Conn. at 513 , 187 A.3d 388 ("[m]ere overvaluation, without more, in an assessment of property is not enough to make out a case under § 12-119" [internal quotation marks omitted] ); see also id., at 513-14 , 187 A.3d 388 ($ 120,000 valuation error on approximately $ 5 million property, which was 2.4 percent, was not manifestly excessive for purposes of relief under § 12-119 ); cf. Griswold Airport, Inc. v. Madison , supra, 289 Conn. at 741-42 , 961 A.2d 338 (because improper removal of airport's open space classification in violation of § 12-504h"caused its assessed value to grow more than eightfold," this court concluded that "the trial court's determination ... necessarily incorporated an implicit finding that the resultant assessment was manifestly excessive"). Accordingly, "we conclude that the circumstances presented here do not rise to the level of the extraordinary situation that would warrant tax relief under the provisions of § 12-119." (Internal quotation marks omitted.) Walgreen Eastern Co. v. West Hartford , supra, at 514, 187 A.3d 388 .

The judgment is affirmed.

In this opinion the other justices concurred.