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  • Contact Information

    Assessor's Office

    assessor@jeffco.us
    303-271-8600

    Monday - Friday
    7:30 a.m. - 5:30 p.m.

    Contact Us

    100 Jefferson County Parkway
    Suite 2500
    Admin and Courts Facility
    Golden, CO 80419

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    Taxpayer Services

    303-271-8600
    Fax: 303-271-8660

    Real Estate Information

    303-271-8666
    Fax: 303-271-8660

    Business Personal Property

    303-271-8693
    Fax: 303-271-8660

  • Inflation and Time Trending

     

    Market Conditions/Time Trending Explanation
    Jefferson County Assessor's Office
    2015 Reappraisal: July 1, 2012 - June 30, 2014 

    Why Time Trending is Done  

    Colorado statutes [39-1-104 (10.2) (a) C.R.S.] require all county assessors to analyze sales data to see what differences, if any, there are between the market conditions at the time of a comparable sale and the valuation date.  Commonly referred to as time trending, sales must be adjusted to the end of the data collection period (July 1, 2012 through June 30, 2014).  Time trending of sales is the usual practice in all types of appraisal work to account for the principle of supply and demand as well as the principle of change.

    Commonly referred to as time trending, sales must be adjusted to the end of the data collection period (July 1, 2012 through June 30, 2014). Time trending of sales is the usual practice in all types of appraisal work to account for the principle of supply and demand, along with the principle of change.

    How Time Trending is Done

    There are several methods used to determine the presence of a time trend.  The one most frequently used within Colorado is called a Sales Ratio Trend Analysis.  It is also the same method used by the auditing firm that will be conducting the 2015 Property Assessment Study used to determine county compliance.

    In general, this method uses the assessor’s appraised actual values from the last reappraisal (June 30, 2012) and compares it against recent sales data that has occurred during the newer period of July 1, 2012 through June 30, 2014.

    This comparison is done using a sales ratio, which is simply the relationship between appraised values and sales prices.  For example, a house that had a June 2012 appraised value of $230,000 and sold two years later, June 2014, for $305,000, would have a ratio of 1.32 ($305,000/$230,000).  What this one ratio indicates is that the property increased approximately 32% from June 2012 to June 2014.  This type of ratio comparison is done to the thousands of sales that have occurred throughout the county.  Ratios are graphed by month of sale, starting with the earliest date, July 2012, and ending June 2014.

    After graphing all ratios, a statistical procedure called “regression” is used.  Regression is able to place a line of “best fit” between all the plotted ratios.  In effect, it is the slope or angle of this line that is used to determine the presence of any significant inflationary or deflationary trends.  An upward line indicates appreciation, downward line depreciation, and a level line no change.

    Last Updated: 4-30-2015
  • More Information on Inflation and Time Trending