MSP Grant
Worksheet: Basic Descriptive Stats for 5th grade
You might find the following links to the StatKey web-site helpful.
Lock5 homepage: http://www.lock5stat.com/
StatKey linked off Lock5 homepage: http://www.lock5stat.com/statkey/index.html
Descriptive Stats for one quantitative variable:
http://www.lock5stat.com/statkey/descriptive_1_quant/descriptive_1_quant.html
Descriptive Stats for one quantitative and one categorical variable:
http://www.lock5stat.com/statkey/descriptive_1_quant_1_cat/descriptive_1_quant_1_cat.html
1. Take your temperature and write it down on the provided notecard.
2. Place your card on the chalk tray, under the number line on the board, in the correct position, and
place a dot in the proper location for your temperature as well.
3. What is the definition of median? How is it calculated when there are an even or odd number of data
values?
4. What is the median of this class’ temperatures?
5. How did the “outlier” temperature affect the median?
6. Estimate the median of the values to the left (smaller) of the overall median. Calculate it with and
without the “middle” value. What is another name for this median of the “smaller” half of data?
7. Do the same as in #6 above for the values to the right (larger) of the overall median. What is another
name for this median of the “larger” half of data?
8. What do you think Q2 is also called?
Note: there isn’t a consensus whether the middle value is included when calculating Q1 and Q3.
9. What is a box plot? What descriptive stats do you need to create it? Write a box plot for the class’
temperature data.
10. What is the definition of “mean” average? Why is it sometimes referred to as the “balance-beam”
average?
11. How does the mean change if the outlier is added to the data on the board? How did it change
compared to the change in the median.
12. You can find StatKey by Googling “Lock 5.” Try this. If you can’t find it, the link is above. Enter the
temperature data in StatKey, using the “1 Quantitative Variable” choice
(http://www.lock5stat.com/statkey/descriptive_1_quant/descriptive_1_quant.html)
13. How do the dotplot, box plot, Q1, median, and Q3 calculated in StatKey compare to the values on
the board?
14. Choose the histogram option in StatKey. Remember that histograms are calculated on one
quantitative variable, and that they have equally spaced intervals, so the height of the bars can be
compared. Use the slider to vary the number of intervals. How does the histogram change? Is there a
number of intervals that captures the data well?
15. The Set Limits button allows the user more control over the intervals/”buckets” of a histogram. By
default, StatKey will use the min and max as the endpoints for the first and last intervals. Use the Set
Limits button to change settings, and note the change in the histograms produced.
16. Edit the data and add the outlier temperature. Note the changes in the mean and median
calculated by StatKey.
17. Edit For more practice in StatKey, consider the temperature data included in StatKey. How does it
compare to the class’ data? The data can be found in the section “Confidence Interval for a Mean,
Median, Std. Dev,” at the URL:
http://www.lock5stat.com/statkey/bootstrap_1_quant/bootstrap_1_quant.html. To find it, click on the
upper-left button for the data, and select Temperature. Then to capture it, click on “Edit Data” and copy
it and paste it into the data for descriptive stats.
Next, we’d like to explore two different datasets, and compare their box plots.
One convenient set of data to use is scores from the National Football League (NFL). These are available
on the www.nfl.com web-page, and it’s nice to compare two teams.
18. Choose a team and enter their point totals from each of their sixteen regular season games. For
example, the number of points the Chicago Bears scored in each of their sixteen 2013 regular season
games are listed below. To find these online, click on a team’s icon at the top of www.nfl.com, find their
schedule, and be sure to choose the 2013 season. Enter each score into StatKey, and calculate the
descriptive statistics for their point totals, as done above for the temperature data. Click on the “Edit
Data” button and select all the scores, so they can be pasted later.
19. What is the difference between categorical and quantitative data?
Next, we would like to compare the box plots of the scores of two different of the teams, and maybe
make a prediction on how those teams might have fared vs. each other. First use StatKey’s: Descriptive
Stats for one quantitative and one categorical variable
http://www.lock5stat.com/statkey/descriptive_1_quant_1_cat/descriptive_1_quant_1_cat.html
20. This requires two columns of data. The first is categorical. What would it be in this case? What is
the quantitative data?
StatKey wants these delimited somehow, usually by spaces, commas, or tabs. Note that if the data is
originally entered in with spaces or tabs as delimiters, StatKey will add in commas. Paste in your original
score data, and add the categorical value for it, team name in this case.
The data in StatKey would look like:
Bears, 11
Bears, 18
Bears, 19
.
.
.
21. Find another team and enter its scores as well. Create box plots for both teams.
22. Which of the two teams do you think had a better season?
23. If these two teams played, who do you expect to win?
24. What on the box plots did you use to help predict this?
25. Did your two teams play? If so, what was the result?
26. Does this agree with your prediction? Why or why not?
Appendix: Points Scored by 2013 NFL Teams
Team
Bears
Bears
Bears
Bears
Bears
Bears
Bears
Bears
Bears
Bears
Bears
Bears
Bears
Bears
Bears
Bears
Points
Scored
24
31
40
32
18
27
41
27
19
23
21
20
45
38
11
28
Team
Vikings
Vikings
Vikings
Vikings
Vikings
Vikings
Vikings
Vikings
Vikings
Vikings
Vikings
Vikings
Vikings
Vikings
Vikings
Vikings
Points
Scored
24
30
27
34
10
7
31
23
34
20
26
23
26
48
14
14