In either case, we should examine the data to help decide whether the normal distribution reasonably fits the data. In this unit, we examine graphical methods for checking whether data are normally distributed. To start, simulate 10,000 draws from a normal distribution with a mean of zero and a variance of one. Make a histogram of these data. A symmetrical histogram is one piece of evidence that the data are normally distributed.
Histograms can be difficult to judge, as their interpretations are sensitive to bin size.
That's no help either. For example, say there are 4 data values. When the data follow a normal distribution, the plot should be roughly a straight line. To make a normal quantile plot, first make a histogram . Then, click on the red arrow next to the column name.