08-28-2012 04:25 PM
Hi, is there a procedure of code in SAS where I can get reference ranges?
For example I have 20 cities with home prices for each month for 2 years for each city.
I do have the standard Deviation and the Coefficient of Variation, but am looking to see if a range of the Prices are more in an optimal range then others.. almost like identifying outliers. So for example if the range of City-A is between 300,000 and 500,00, is optimal, anyhting outside of that range is considered an outlier, or whatever term you may call it. Thanks
08-28-2012 07:15 PM
Try the UNIVARIATE procedure. It identifies your lowest and highest values plus percentiles, means, medians etc. You could use a BY statement on your city variable to look at percentile variations between cities.
08-29-2012 08:04 AM
Agreed, Doc. But how about generating that reference range for the 'first' time? Lately, I have been tasked with doing something like that with historical control data in tox studies. UNIVARIATE is my tool of choice--normality testing, percentiles, etc. Ultimately, I want to incorporate this info as a prior distribution for some Bayesian analyses.
08-29-2012 09:18 AM
Often the "reference range' comes from historical controls. Sometimes from specific analysis of known normals (typical for clinical lab tests). I worry about podarum's approach of using the 'study data' to derive the ranges, particularly for housing prices (we know they have been problematic over the last several years).
08-30-2012 08:01 AM
I agree about using 'study data' for ranges--it's like using EDA methods as confirmatory stats. Of course you find something, you just spent 15 hours digging around looking for anything shiny.