An investigator cannot observe the entire population but only the four samples selected at random for treatment. This figure shows the same four groups of
individuals as in Figure 3-1 with their means and standard deviations as they would appear to the investigator. The question facing the investigator is: Are
the observed differences due to the different diets or simply random variation? The figure also shows the collection of sample means together with their
standard deviation, which is an estimate of the standard error of the mean.
Source: Chapter 3. How to Test for Differences between Groups, Primer of Biostatistics, 7e
Citation: Glantz SA. Primer of Biostatistics, 7e; 2012 Available at: http://mhmedical.com/ Accessed: July 12, 2017
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