How to get Wikipedia data that helps you estimate market sizes
Wikipedia has useful data that can inform market estimates. This includes numbers of households and various lists of public companies revenue data.
Data sets like these help you do market estimates, particularly when you estimate "reasonable upper bounds" on market sizes (-> "is it plausible that this market is or gets as big as this estimate says?"). For example, for a B2C product, if you see a market size estimate that would require there to be ten times more households than there are, this estimate is very likely too high. Similarly, for a B2B market, if the market size estimate is substantially bigger than the total revenue of the biggest target companies in this market, the estimate is probably too high.
Economic data sets on Wikipedia
Here are some examples of the economic data you can find on Wikipedia (there are others too, but the ones below are a starting point):
How to import data into Google Sheets
In Google Sheets, the relevant function is IMPORTHTML. For example, if you want to make a GSheet with companies by R&D spending, you need the following function:
And the result looks like this:
How to import data into Excel
In Excel, importing data from Wikipedia works like this (using the same data as above, companies by R&D spending):
1. From menu "Data", select "From Web"
2. Enter the Wikipedia page URL, and select "Advanced"
3. Select the table you want, then hit "Load"
The result looks like this: