For those who rely on Excel to do their data analysis (rather than mini-tab or JMP), occasionally the charts available are a little limiting. So I thought I would post this technique to allow you to perform a box plot analysis using Excel. Collate the data First you need to gather your data together. In this example, I have 10 sites, with values by month for the year 2011. For clarification, I have also uploaded the excel file, so please feel free to have a look! In the example attached, I have created a tab in excel for each site (labelled 1 to 10). You can of course use just one tab for all if you prefer!

The first thing you need to do is calculate the median, minimum, maximum and upper quartile values for each site. You can see this on the “Box plot” tab of the excel sheet attached. The median is calculated by: =MEDIAN(‘1’!$C$2:$C$11) ‘1’ refers to tab “1” and it is looking at the values in column C from lines 2 to 13. Repeat this for each site (and tab) by changing the figure ‘1’ to ‘2’, then ‘3’ etc to form row 2 of the table below. The $ symbol ensures that the range used for column C never changes when you copy / paste the calculation across the row.

Mar 30, 2011 - I cannot download my new Windows 7 Home Premium, because the first download is a.box file extension. I've downloaded (and paid for). Far cry 1 download. Software to open or convert BOXCHART files It looks like we do not have any suggestions for programs that can open BOXCHART files. We receive hundreds of suggestions from our users every day, so suggestions for.BOXCHART may become available quite soon.

I will come back to row 3 in a moment, for now let’s skip on to rows 4 and 5. The minimum is calculated by: =MIN(‘1’!$C$2:$C$11) The maximum is calculated by: =MAX(‘1’!$C$2:$C$11) Again, repeat this for each site (and tab) to form rows 4 and 5 of the table above.

The minimum and maximum values will be used to create the whiskers of the box plot. Now let’s go back to row 3. Excel has a built in function “quartile” which we can use for the calculation for this row and for row 6. Row 3 ( Lower quartile, Q1) is calculated by: =QUARTILE(‘1’!$C$2:$C$11, 1) The value after the comma (in blue above) show that we want the lower quartile (Q1) Row 6 ( Upper quartile, Q3) is calculated by: =QUARTILE(‘1’!$C$2:$C$11, 3) Once again, repeat this for each site (and tab) to form rows 3 and 6 of the table also shown below.

The Q1 and Q3 values will form the top and bottom of the box. The order they appear in, (median, Q1, Min, Max, Q3) is very important! Do not change this or the graph will be wrong!

Create the chart Since excel doesn’t have a box plot chart we are going to have to create one. To do this, first select the data table shown above, then on the Insert tab, click on the small down arrow next to Other Charts in the charts section. Click on the 4th chart in the Stock section (Volume-Open-High-Low-Close.

You will need five series of values to create the graph). Excel will automatically create the graph below. This is not exactly what we want, so we will have to do some formatting. The first step is to adjust the two Y axes so that they are identical, i.e. Both go from 0 to 4.0. Double click on the left axis. In the menu that apears, ensure that Axis options is selected, then change the maximum value from Auto to Fixed and enter a value of 4.0.