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Descriptive Statistics Help

SPC for Excel will generate descriptive statistics for one or more sets of data. There is the option to include a dot plot and histogram for each set of data.


You want to get a quick overview of the performance of three machines. The data you have collected are shown below.

Descriptive Statistics Output

The output for the descriptive statistics is shown below.

The standard error is the standard deviation divided by the square root of the sample size (count). The 95% upper and lower confidence intervals are calculated from the t distribution as the average +/- t(standard error) where t is the value of the t distribution for alpha = 0.05 and the degrees of freedom associated with the sample size.

If the option for the dot plot and/or histogram was selected, the charts are placed on a new worksheet. All the charts for each variable are placed on that worksheet. The dot plot for Machine 1 is shown below. The frequency for each data value is given on the y axis.

The histogram for Machine 1 is shown below.

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