How much does it really cost to rent an apartment in San Francisco? It depends on who does the counting.

While most rental sites continue reporting median prices well beyond $3,000/month, one broke from the pack in May. It claims other reports are crunching the numbers incorrectly and that a more realistic figures is about two-thirds of that number.

Representing the status quo opinion, rental site Zumper released its monthly analysis for June, continuing its 2017 trend of good sounding news that no one could possibly enjoy.

Median San Francisco prices are down over six percent compared to last year, but it’s hard to get excited about that when a single-bedroom apartment still goes for $3,370/month on Zumper.

Competitor RENTCafe more or less agrees, reporting that the average new renter can expect to pay $3,369/month for a one-bed, down 3.3 percent from the same time last year. Abodo says $3,284/month.

And then there’s ApartmentList. According to that San Francisco-based site, market rates for a one-bedroom are more like $2,410 (down one percent since 2016).

The huge discrepancy happened because ApartmentList recently changed how they crunch their numbers. According to the site’s blog:

Data from private listing sites, including our own, tends to skew towards luxury apartments, introducing sample bias. In order to address these limitations, our estimates now start with reliable median rent statistics from the Census Bureau, which we then extrapolate forward to the current month using a growth rate calculated from our listing data.

While we tend to think of statistics as objective and reliable (i.e., “hard numbers”), in practice, methodology is everything.

ApartmentList’s data scientist Andrew Woo suggests that rental sites work off of biased samples. The U.S. Census and HUD provide more reliable data, but only once a year. Woo now wants to use the federal numbers as a guide to correct the “real time” ones.

So, did San Franciscans enjoy a $1,000 rent break this year, or is it just a statistical illusion? Well, Craigslist currently lists over 400 single-bedroom homes in the $2,100-$2,400 range, but only about 300 in the $3,000-$3,300 bracket.

That looks compelling, but Craigslist isn’t an unbiased sample, either. In a few years, the census will report what it estimates average prices were now, which may or may not vindicate one set of numbers or another.

Until then, most renters have only one number on their minds: The one they’re paying now.