Mozcast Review

Updated 12 May 2021 by Max

What Is MozCast? Review


MozCast is an experiment in tracking the “weather” patterns of the Google algorithm. While big updates like Panda and Penguin get a lot of press, Google revealed that they made 516 changes in 2010, and all evidence suggests that pace has continued. What we notice is barely the tip of the iceberg. MozCast was designed to help you keep track of the day-to-day changes in the Google algorithm.

How Does It work?

It all starts with this: every 24 hours, we track a hand-picked set of 1,000 keywords and grab the top 10 Google organic results. Keywords were deliberately chosen to avoid obvious local intent, are distributed evenly across 5 “bins” by query volume, and are tracked at roughly the same time every day from the same location. In other words, we do our best to keep the data set tightly controlled.

Each day, we take the current top 10 and compare it to the previous day’s top 10 (for any given keyword), and calculate a rate of change or “delta”. Specifically, we use two metrics – called Delta 100 and Delta10 – which measure the change across the entire set of top 10 results. Then, we crunch Delta10 across all 1,000 keywords and multiply the resulting average by a fixed multiplier (currently, 28.0) to produce something that looks like a temperature (in °F). An average day is about 70°F.

So, What’s a Delta10?

Ok, here’s the more complicated version of the story. We tried a lot of metrics for comparing two sets of top 10 results, and we ultimately landed on two that seemed to work pretty well but were simple enough to explain. The first is “Delta100” – for any two days of top 10 rankings, it gives us a number from 0-100, calculated by the following rules.


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