2022 Introduction to Statistics in Research Mitchell 2nd ed

I N T R O T O R E S E A R C H : D A T A V I S U A L I Z A T I O N & C O M M O N S T A T T E S T S

Even though Chart 1 uses the same data, the story is difficult to tell. Always convert your data to frequency percentage when you have different sample sizes! (Quiz)

Box Plot or Box-and-whisker plots

Box plot or box-and-whisker plot is a great visual for exploratory data analysis. They are an extension of the five-number summary which consists of the median, the upper and lower quartiles and the largest and smallest observation. Box plots are used a lot in business decisions because they are considered "resistant statistics". The median and quartiles are highly resistant to change (Quiz).

To really understand the power of box plots, let's look at three schools that want to compare their student's scores in English, Physics, and Math. Here is the data already formatted as a table. That way, you can use the drop-down arrow to sort by course or by the school.

Table 54: Scores for English, Physics, and math at three difference schools

The box-plot shown below was created in Excel. Excel has a much more appealing visual than SPSS, JMP, R, or even Statistics Kingdom. A box plot chart is available in statistical charts in Excel. These box plots are shown in horizontal format since there are three schools to compare.

Table 55: Excel Box Plot

70