What I found is everyone has their own measurement and vendors especially skew that measurement to their benefit. You're best developing your own standard measurement and don't deviate from that measurement.
For example here's what I use for our Lead Conversion Rate on our Website(s) and mobile site - I seperate mobile from desktop numbers:
Shoppers - Unique Visitor who visits at least one inventory page
Lead - Fresh (careful including these), Phone (unique tracking on sites), or Form Submission
Form Lead - Exactly that, form submission from VLP or VDP
Phone Lead - Phone call from tracking number
Solds - Website Lead who purchased
To Calculate:
Lead Conversion Rate = Leads/Shoppers
Lead To Sold Rate = Solds/Leads
Shopper To Sold Rate = Solds/Shoppers
When Comparing numbers, I only compare like quarters, like months to previous year, and previous month, maybe two months back. One thing I've notice is your numbers will fluctuate throughout the year and then trend like other years. Comparing like months will help eliminate yearly trends. You will have outlier months - like January of 2012 we had 70+ degree temps vs January 2013 we had 1'+ snow and cold temps. Make note of those in your analysis.
