Here are the data from exercise 1.26
presented as a split stemplot:
Type the data from the stemplot into
your Excel spreadsheet starting at the cell A1. The first rows
should look like:
Click on "Tools" from the menu bar
and then click on "Data Analysis Menu".
If you don't have the "Data Analysis..."
Option that appears on the bottom of
this menu, you need to load the "Analysis
ToolPak" as discussed on the
Primer tutorial page. This should give a window
something like:
Click OK to pull up the "Histogram"
window.
Then fill in the options exactly like here:
Note that the output range allows you to
choose the cell where the upper left corner of your output will be
positioned.
Click OK. You should get something
like:
Warning: The bins of the histogram have been chosen by Excel and by selecting other bin sizes we can improve the histogram.
We would like to obtain a histogram similar to the stemplot, hence we choose the bins limits as 10,15,...,60, and write those numbers into the cells C1:C11. Then,
Delete the histogram chart. Highlight
the entire area of the chart and the table and then choose "Clear
" and "All" from the "Edit" menu:
Note. If instead of deleting you'd like to keep the histogram chart, then be sure that you choose E17 instead of E5 for the "Output Range " below.
Pull up the "Histogram" window
again and then fill in the options exactly like here:
Click OK. You should get something
like:
The new histogram is closer to our initial
stemplot, but if we choose the bin limits as 9,14,19, ... ,
we will get the following histogram, whose
frequencies are exactly as the leaves of the stemplot:
A better looking histogram can be produced using the "Format" option from the menu bar:
Click one of the bars
in the histogram, then select "Format" and click on the "Selected
Data Series".
Select the "Options" tab and then
adjust to zero the "Gap width".
*Warning*
The default numerical labels on the horizontal axis are, to say the least,
NOT optimal. First of all, they
are shifted too far to the left relative
to the tick marks: the "9" in the above histogram actually applies to the
tick mark
immediately to the left of the first blue
bar; then the "19" actually applies to the tick mark immediately to
the right of
the second blue bar. You may get numerical
labels for each tick mark by stretching the chart. The other "not
optimal"
feature, the tilting of the labels, may be
adjusted using the "Alignment" tab from the "Format axis" menu.
Here are Cavendish's 29 measurements of the
data density of the Earth presented as
a stemplot:
Question 1. Make a histogram of these measurements, with the
bins chosen such
that
the histogram bars represent the same frequencies as the stemplot leafs.
Then briefly discuss the main features of the distribution on the next
two rows under the histogram chart. Next write in the cell D1 your
estimate of the density of the Earth based on these measurements.
Hand in the printed Excel worksheet.