Yesterday I did a chi-square goodness-of-fit test with my class comparing a large sample of M&Ms – over 800 of them – to the data that is provided by Mars for the true count of M&Ms. We got a p-value of 0.0002, which seems crazy. So now I simply need to know how accurate their data actually is.
So here is my proposal: if you do an activity that involves counting the various colors of M&ms in any random sample, any year, add your data to my collection using the form below. If you buy a bags of M&Ms and just feel like counting it, add data. If you want to put young children to work counting M&M colors, add their data too. If you have data from previous years, great! Add that too, and maybe I can add a time component to the analysis. If we get enough people on board, we should start to get an accurate picture of the true proportion of M&M colors, to see if Mars tells it true.
I have embedded the form and part of the analysis below, but you can also click here to access the full Google Sheet with the analysis of the total data, analysis by year (currently only 2015 makes sense obviously) submission-by-submission analysis, and original results.
[Note: I also had to make my own chi-square cumulative distribution function for Google Sheets, borrowing some source code from this online calculator at UCLA. If you want to know how to use it, or make your own custom Google Sheets functions, e-mail me and I can advise.]