Plotting the distribution of the data

Before summarizing data with descriptive statistics or making inferences about parameters it is important to look at the data. It is hard to see any patterns by looking at a list of hundreds of numbers. Equally, a single descriptive statistic in isolation can be misleading and give the wrong impression of the data. A plot of the data is therefore essential.

Open the file tutorials\Speed of Light.xlsx.
Click a cell in the dataset.
On the Analyse-it ribbon tab, in the Statistical Analyses group, click Distribution and then click Mean and Central Moments.
The analysis task pane opens. A histogram, univariate plot, and descriptive statistics are added to the analysis task pane.
In the Y variable list box, Select Speed.
Click Calculate.
The results are calculated and the analysis report opens.

The histogram of the data shows a normal distribution except for two outliers.

frequency histogram

Next topic: Estimating the population mean