Science 294
DSH Winter, 1997 revised 15/7/01
Exercise #15. Descriptive Statistics with Excel
In the natural sciences data are frequently summarized and compared using the mean,
standard deviation, standard error, and 95% confidence limits. In this exercise you will learn
how to quickly determine these statistics and make a table using EXCEL. You will also learn
how to use EXCEL and WORD to construct an appropriate graph, termed a Dice-Lerass graph,
which portrays these data (see the last figure in this handout). Lastly you will learn how to
import the table and graph into a WORD document as you would for preparation of a report in
either chemistry or biology.
Descriptive Statistics in Excel
Various statistics can be computed in Excel in a number of different ways. One method
is to simply use some of Excel's Data Analysis Tools. Give this a try by making an Excel file out
of the data set in Table 15.1, and then obtaining descriptive statistics using Tools: Data
Analysis…: Descriptive Statistics.
Table 15.1 Heart rates (beats/minue) of male and female non-smokers and smokers.
Male-nonsmoker:
male-smoker:
female-nonsmoker:
female-smoker:
65, 63, 73, 58, 54, 68, 52, 58, 53, 69, 64, 63, 58, 63, 67
74, 70, 71, 63, 71, 77, 70, 76, 70, 81, 76, 81, 73, 79, 77
66, 62, 60, 52, 63, 61, 57, 54, 59, 62, 64, 53, 54, 62, 64, 63, 72
69, 61, 70, 75, 67, 68, 76, 65, 66, 73, 76, 71, 76, 67, 63, 73, 55
One can also use built-in Excel functions to calculate the needed statistics. This allows the user
to construct an individualized data analysis package. You will now be instructed in the
construction of such a package.
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Exercise 15. Excel Descriptive Statistics
Science 294
Excel Template for Descriptive Statistics
1) Open a Workbook in EXCEL 98. Fill out the labels
in column A (following the example provided
directly to the right. ). Make the column autofit
the widest label.
2) Construct the formulae required to determine each of
the variables assuming the data are placed in
rows 14:100 of column B. As your data use the
first row of data in Table 15.1.
Many of the calculated variables are
functions and can be found using the paste
function icon (or Insert:Function). Some
calculations are briefly described here.
a) Standard error is computed by dividing the
standard deviation by the square root of
the number of measurements (count or
n).
b) t (0.05,n-1) is the TINV where the degrees of
freedom are the count minus one.
c) 95% confidence limits for individuals are
equal to the mean ± the standard deviation times the t value.
d) 95% confidence limits for the mean are equal to the mean ± the standard error times
the t value
The data are to start in B14. To check to see that your formulae are correct, you should use the
first row of data from Table 15.1.
3) After you are positively sure that the calculations are correct then copy the formulae from
B2:B12 to columns C, D, E and F. Copy the data from column B14:B30 into columns CF to make sure that the formulae in rows 2:12 are working.
4) Clear all the data from B14:F30. Save the workbook as a template using the name
"DescStat.tmp." Close EXCEL.
5) Reopen EXCEL and the file "DescStat.tmp." Note that the name of the file has now changed
(to what?). This is because you saved it as a template.
Now enter all the data from the file "DescStat.dat" into your template starting at
row 14 (B14:C14:D14:E14). If you have done everything correctly the descriptive
statistics should be calculated automatically. Your DescStat.tmp" file should look like the
one on page 1.
Congratulations, on successfully completing your first Excel template!
6) Save this file using a name different from what it opened as (you must, of course, use the Save
As option).
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Exercise 15. Excel Descriptive Statistics
Science 294
Table Construction
1) Save the file yet again but this time as a text file (ASCII file) with tab delimiters. I typically
append ".txt" to the name of the file. Close the file, and then reopen it.
When the file is reopened all the formulae are gone and only the numbers are left
behind. The numbers can be manipulated into a regular table format while this could not
be done with the formulae.
2) Copy A1: E14 and open a new workbook. Select A1, choose File: Paste Special:
Transpose:OK.
3) Delete all the columns except those shown below in Table 1. Then save the file as a text only
with a unique name.
4) Transport the table from EXCEL to WORD by either a) copying the table in EXCEL and
pasting it into a WORD document or b) opening in WORD the text file created in step 3.
5) Use Word to format the table in a nice fashion similar to that shown here.
Table 1. Caption to be constructed by students.
n
mean SE
95% Confidence
Limits
Range
Nonsmokers
male
female
15
17
61.9
60.5
1.6
1.3
58.4 - 65.3
57.8 - 63.1
52 - 73
52 - 72
Smokers
male
females
15
17
73.9
68.9
1.3
1.4
71.2 - 76.7
65.9 - 71.9
63 - 81
55 - 76
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Exercise 15. Excel Descriptive Statistics
Science 294
Figure construction
1) Reopen the EXCEL file created in B3.
2) Remove all the columns except for mean, low and high 95% confidence limits of means,
minimum and maximum. Each value has to be in its own column.
3) Select the remaining data but not the column headings (e.g., A2:F5); note you must include the
labels (e.g., “male”) in column A.
4) Select the Chart Wizard. Make the following selections in the Chart Wizard Steps.
Step 1 XY (Scatter) Chart type 1 (1st format, no lines)
Step 2 Data Range: select columns
Step 3 Titles nothing in Chart title
Value (X) Axis: leave blank
Value (Y) Axis: Heart rate (beats/min)
Gridline uncheck all boxes
Legend uncheck Show Legend
Step 4 Select "As object in:"
5) A graph should appear similar to the one
to the immediate right.
6) The graph needs lots of modification so
that it appears like the one
immediately below the one to the
right. The following changes are
required.
a) Remove the border and area fill
by double clicking in the
middle of the graph (plot
area). Select None for both
the border and area.
b)Change the scale on the X axis
(minimum=0;
maximum=4.5, major
unit=1; minor unit=1; Value
(Y) axis crosses at=0)
c) Change the scale on the Y axis
(minimum=50;
maximum=85, major
unit=10; minor unit=5;
Value (X) axis crosses
at=50)
d) Change the tick mark type of
both the axis to "inside."
e) Remove the border around the outstide of the figure by clicking in the "chart area"
outside the X & Y coordinates and selecting no border in the patterns tab.
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Exercise 15. Excel Descriptive Statistics
Science 294
7) Save the graph. I usually add the suffix of ".plt" or .".gph" to remind myself that the file
contains a graph.
Decision Point. It is at this point that one has to decide whether to finish the figure using ink and
a ruler, or using some computer drawing program. If the former, then one should do two more
operations before moving the figure into Word where the caption can easily be added.
8) Change the X axis labels from numbers to the appropriate descriptors. Select the X axis so that
the Format Axis window appears. Select Font: Color, white: Background, transparent.
This will eliminate the numbers on the X axis. Enter the appropriate labels one at a time
by selecting the graph, typing the desired letters, hitting return, selecting the text and
moving it to where you wish it. You then need to select outside the graph. Then repeat
until you're finished. After this is finished one can use ruler and ink to put in the
appropriate lines shown in Figure 4.
9) Change each of the points on the graph to the smallest possible symbol so hand-drawn
ink lines will obscure them. Do this by selecting each one of the points and double
clicking on it. Then make the marker style be a black small horizontal tick.
If a computer drawing program is to be used, then deleting the points and inserting the X
axis labels might more easily done in that program. I personally use MACDRAW PRO and it is
very easy to put in the labels, lines, and rectangles required. CLARIS WORKS, available to you
on the server disk also seems relatively easy to use. One can also do it using either the drawing
portions of WORD or EXCEL. Both are tedious and take time. Based on repeated failures in my
attempts to do this, my advice is to save, save, save every step that is successfully taken.
Following is how I completed the figure using the drawing portion of EXCEL 98. First, I
did step 8 above. Then I did the following.
10) Open the Drawing Toolbar (View: Toolbars: Drawing) and then select the figure. Use the
drawing toolbar to put in the lines, rectangles, etc.
11) Use the Drawing line tool to put in the vertical line representing the range from the highest to
lowest value. As your putting in the line depress the shift key and it will make the line
straight vertical. Use the rectangle tool to put in the rectangle representing the 95%
confidence limits. Then put in the mean line using the line tool (shift key down for
straight horizontal line). You can fill the rectangles by selecting them and using the fill
color drawing button (fill color: fill effects: patterns). Lastly, eliminate each of the
original symbols indicating a s variable (e.g., mean) by double-clicking on them. Select
the none button under Marker. The data points should disappear from the graph.
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Exercise 15. Excel Descriptive Statistics
Science 294
Heart Rate (beats/min)
80
70
60
50
0
Male
1
Female
2
NonSmokers
Male
3
Female
4
Smokers
5
Figure 15.1 Caption to be constructed by students
Finished Product
1) Transfer the table and the figure into a single new WORD file. Place the figure above the table
and separate them 1.5 point border. Write captions for both the figure and table (figure
caption on bottom, table caption on top). Place your header on the single page and be
prepared to hand it in.
2) Prepare another page to hand-in. This page should contain your header and the following three
pictures.
a) Picture one should be of your Table and should clearly show that you used styles, and
followed the main rules of word processing of never hitting the space bar or tab
key more than once sequentially.
b) Picture two should be of your Excel template and should include the reduced values for
the heart rate data.
c) Picture three should also be of your Excel template but should clearly show the
formula used in the template.
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