I edited The Oregonian/OregonLive article on opioids and pharmacies that your publication critiqued on Aug. 23. Our report was based on The Washington Post’s national ranking of pharmacies by opioid pills purchased, per county resident, per year. You raised concerns about the analysis, which put Howard’s Drugs, in Lake County, and Len’s Drug, in Grant County, in the top 0.1 percent of 83,000 pharmacies in the country.

There is a shortcoming to the Post’s approach. Dividing every store’s pill purchases by its county population dilutes the rates for urban stores, most of which serve only a fraction of their urban markets.

Prompted by your article, we asked the Post about its methodology. Investigative Editor Jeff Leen said that the ideal measure would have been a pharmacy’s pill orders per actual opioid customer. That information was not available from the database, so the Post used an imperfect measure that had support from experts. The choice was made after consultation with mathematicians for the parties suing opioid manufacturers. The Drug Enforcement Administration has used the same methodology to identify pharmacies for scrutiny. Speed and simplicity were also factors in the Post’s decision to publish the numbers while it continued to work on a more nuanced ranking system.

Is there a fairer way to compare urban and rural stores? Since publication, we’ve tried a different method to address the issue of market share raised by the Eagle. We divided each county’s population by its number of stores. Howard’s and Len’s would remain outliers, but not as extreme as in the Post’s rankings. They would be in the top 11 percent and 8 percent of stores nationally, but so would dozens of other Oregon stores, and thousands across the country.

Of course, this method has its own issues. Some urban pharmacies presumably have a much bigger market share than others. Many serve commuters from suburban counties as well as local residents.

For another perspective, we examined the Post’s rates for stores in counties averaging less than 1.5 pharmacies in business from 2006 to 2012 (Grant County’s status today). Out of 435 similarly situated, rural stores nationwide, Howard’s rate was higher than 430. Len’s was higher than 400, and it’s worth noting that one other pharmacy served Grant County throughout this period.

Much to their credit, the two Oregon pharmacy owners gave us lengthy interviews and provided needed context that we included in our article. The Lake County owner noted that his was the lone pharmacy for local residents, and the Grant County owner noted the higher rates of injury in rural jobs.

We very much appreciate the Eagle’s reporting on this. We will be publishing an editor’s note to highlight the limitations you have identified. In the end, the Post’s ranking system identifies outliers, but other methods put urban stores at the very top. Our story lacked important caveats acknowledging the challenges of reaching a meaningful common denominator. Your story is leading us to rectify that in print and online.