45 that's a lot of sales. Try working with 7 sales in a market in the past 6 months in a declining market. Can you say dissertation?
Generally the way to properly identify a declining market is to compare average sales prices from point A to B, A to C, A to D, A to E, A to F and A to G in a from 6 to 5 month ago period, 6 to 4 month ago period, 6 to 3 month ago period, 6 to 2, 6 to 1 and 6 to today. If the overall average sales price in that market continues to decline even as the pool is getting bigger in adding the next month of sales into each average, than you have yourself a declining market.
To further prove the declining market underwriters ask us to apply the overall average of decline in the market per month as a percentage based on how long ago the comparable sold (i.e. let's say the overall decline in 6 months is 9%, that's 1.5% average a month of decline, the comp sold 3 months ago for 500k, 500k x 1.5% = $7500, $7500 x those 3 months ago = $22,500, your time adjustment for that comp is -$22,500).
They also ask to provide a few pending sales or comparable listings. When applying comparable listings we are asked to take the overall sales price to listing price ratio of the comparable sales we used and apply that percentage to the listing price to arrive at a negative adjustment for "probable negotiations." If the average sales price to listing price ratio of the 3 comparable sales is 95%, and the listing price of the comparable listing is 525k, than the adjustment is 5% of 525k or -$26,250 or -$26,000 rounded.
These are some of the ways that declining markets are justified and accounted for. God I hope it turns around soon because doing all this extra work per report for no extra charge sure is fun!