If you are in marketing analytics, this is a problem you encounter often. The site conversion rate varies from one period to another, how do you explain the difference? Is it because we have more traffic from certain high converting channels or because we have a change in conversion rate? The mix-rate bridging analysis can help you connect the dots.

P.S.  As a club member — you can access the google sheet template here.

Let’s use the data from my Etsy store as an example.

My Etsy store’s traffic comes from 5 channels, and the overall conversion rate increased from 1.82% to 2.46%. You can see there are traffic mix changes and conversion rate changes for each channel, what’s contributing to the increase in CVR?

1. Prep the data

Calculate the mix (% of total traffic) and rate (conversion rate) for each channel.

2. Mix change

Assuming the CVR in period 1 stays constant in period 2, looking at mix change alone (% of total traffic in period 2 — % of total traffic in period 1), how much each channel is contributing to the CVR change.

mix change = CVR in period 1* (% of total traffic in period 2 — % of total traffic in period 1)

You can see social media has the biggest positive mix impact as we divert more share of traffic to this high converting channel.

3. Rate change

Given the mix in period 2, what’s the change in CVR in each channel that contributes to the conversion rate?

rate change = (CVR in period 2 — CVR in period 1)* % of total traffic in period 2

Direct & other traffic had an increase in CVR that translate to the biggest impact on rate change due to its high mix in period 2.

4. Bridging

The mix and rate change bridge together the change in CVR (+0.64%) with rate overall had a -0.069% negative impact and mix had a +0.71% positive impact.

You can also diagnose each channel to see how you can improve them. For example, Etsy app & Social media both had a positive mix impact but negative rate impact, indicating the increase in volume either didn’t bring in high-intent traffic or their purchase flow needed improvement (if any changes were made there).