8.2 Five marbles and the standard error of the mean




Materials required are marbles and a 200 gram scale. As was done last spring, this term a mix of marbles was used. 



This term the current term spreadsheet was not properly setup. Column C was accidentally wiped along with columns A and B. This wiped F2, F3, and the corresponding cells below in F. 

Students were given five marbles. This avoided an issue that had been created by giving students five of the same marbles. When different sets of five were in use, some were the smaller, lighter blue marbles and these would generally not capture the population mean.

A spreadsheet, single tab for the Smartboard memory limitations, is used to generate data. 

After the first five marbles were massed the point estimate of the population mean was 5.22. The massing was paused to explain that this was the best estimate of the population mean for that student. The point estimate for the population mean. 


By an absolute accident, Kozel wound up with five 5.2 gram marbles, a standard deviation of zero, and a standard error of the mean of zero. 



The Smartboard was used to show the relationship between the sample standard deviation and the standard error of the mean. Here the distinction between the population standard deviation and the sample standard deviation is being played with fast and loose. 

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