I do agree with the article that reporting rates for that loan would be better than some average. If I were in charge that is what I would try to do. Given that I am not, I am willing to accept average - though I wish we didn't have to. I do not think we should accept wrong data though.
There claims about Kiva under-reporting the rate are worthy of response from Kiva in my opinion, but the claims don't seem to be proved to me. It is possible, in fact it should be the case, that Kiva loans from a lender are less than the average portfolio of the lender. Part of the idea of Kiva is to provide interest free (to the "BANK") capital. The Kiva partner "banks"/financial charities... still have other costs of servicing the loan that have to be covered with interest but they don't have to add to that the cost of capital for Kiva loans. That is my understanding about the concept anyway.
If I understand the post correctly they are taking a 2nd organizations estimation of loan costs to borrowers from lenders. And showing those are higher than Kiva reports. But part of the idea with Kiva is that the lenders can loan for less because they are getting free capital (with other capital they may well have to pay interest) so it could be perfectly accurate that Kiva's rates are what Kiva borrowers pay and those other rates are what averages for the whole portfolio of the lender without. In which case it doesn't mean Kiva's rates are wrong.
If Kiva is not managing the financial data well enough to accurately report those figures that is bad. I don't see enough evidence from that post to say they are - though as I said, I would hope Kiva addressed (or will address that claim).
While I am mainly defending Kiva here (because my opinion is that it is mainly good, though could be more transparent) I think it is good that people challenge Kiva. And I wish Kiva was more transparent.
To get good data likely costs money - Kiva has to hire people to assure the accounting is accurate, train people, etc. Given the challenges it may well be hard to do it all at once. If I ran Kiva I would do so with a set of long time parters now. I would indicate that they have this higher level (more accurate and more current) portfolio yield. I would make sure we had good ideas on how to do this from working with a set of partners. Then I would deploy the new improvements to more partners.
People sometimes forget Kiva is doing some pretty amazing stuff. Many of these partners barely have internet connections, they don't have CPAs working for them, they have some very well intentioned people. I do also believe there are probably scams going on. Kiva has quite a challenge to keep that all under control.