Google conversion tracking discrepancies?

I've seen conversion tracking discrepancies, has anyone else?

[mkelly7777]

I have an Adwords campaign I've been running for 6+ months. I measure sales of our software product (it has a 14 day free trial) using Google's conversion tracking code, and I also measure sales through an internal system on our Web site.

Has anyone else noticed that Google's conversion numbers change over time? For example, back in October I ran a report through Google for a particular week in October and got 57 sales. I just ran a report today, 12/4/05, through Google for the same week in October and I get 77 sales!

Has anyone else noticed this kind of time lag in Google conversion tracking?

Also, this week my internal system reported 100 sales through Google ads and Google only reported 77 - anyone had this kind of underreporting?

Thx.

[Stratcat]

I've noticed discrepencies in Conversion tracking for my campaigns but I haven't taken the time yet to figure it out.

So bottom line is yes, Google's reports don't seem to be very reliable.

[mkelly7777]

Thanks for you reply.

I know Google used to say that their conversion tracking cookie only tracks sales that happen within a 30 day period (30 days from when a user clicks on your Google ad). My internal tracking system has no such limitation. I wonder if this is a reason why I see higher conversion numbers?

[Robsp]

Google reports a sale back to the date the click occured (provided it is within 30 days). So with your trial software it is likely that users first download the trial version after they click and then buy after some time. When they do the sale is reported at the original click date. It is supposed to work this way.

[mkelly7777]

Wow, I had no idea that if someone bought 10 days after they clicked on my ad, the conversion would be applied in Google's reporting system on the same day they clicked on the ad (as opposed to the day they actually buy).