Computer Science and Computer Engineering 115
Solve it with the Computer!
Fall 2006

Lab 9
Descriptive Statistics

Goal:

In this lab you will "describe" a couple of data sets using some standard descriptive statistics and a histogram.

Preparation for the lab:

Review the slide show handout Stat1.ppt. Also download the file lab09.xls from the Statistics download folder http://www.cs.plu.edu/courses/csce115/fall06/download/statistics/

The exercise:

The final percentages for students in two previous CSCE 115 classes are provided. The data includes all students who completed those courses. In the appropriate places calculate the specified descriptive statistics. In the frequency table supply the counts of the number of times a score exists in the specified range in the specified class. Then create a histogram from that data.

In this lab you can get the counts either from the FREQUENCY function or by manually counting them. We will cover the FREQUENCY function in class. If you want to finish the lab before we cover that function, you can count the frequencies by hand. Hint: counting manually may be easier if you make separate copies of the two data sets and use the sort operation to sort them.

You can format the sheet as desired subject to these rules:

• Input cells must be colored differently than formulas cells.
• The final sheet must be sized to print on one sheet of paper so the sheet could be included in a report. You can check this without actually printing using Print Preview in the File menu or the Print Preview tool button.
• The completed sheet must be formatted well enough to be used a formal report.

Additional comments:

The lab09.xls file has several comments that should clarify several questions about the lab. Be sure to include all the boxed rows with the "class 1" data set when calculating the statistics. The blank cells will be ignored. There are two reasons for doing so. It will allow the sheet to be used for another bigger class sometime in the future. In addition that will allow you copy the descriptive statistic formulas from class to the other.

A few formulas have been provided in Lab09.xls. You may want to check them out. In column K, the CONCATENATE function is used to concatenate text strings. That is, it takes 2 or more strings and connects them together end-to-end to make a new string. For example CONCATENATE("A", "BCDEF", "GHI") = "ABCDEFGHI". The TEXT function is used to convert numbers into text so they can be used with the CONCATENATE function that only works with strings. "0%" parameter means that when converting the number to a string, make the the string look like a percentage. The net result is that if you change the values in column I, the values in column J and K will automatically be updated. (Try it.)

Grading:

Your spreadsheets will be graded on meeting the requirements, correctness, general looks, and impression they leave the reader.

Submitting your workbook:

1. Use the URL http://www.cs.plu.edu/submit/login.php
2. Select your class (csce115, Fall 2006) from the drop down box.
3. Enter your submit system username and password.
4. Click "Login".
5. In the add Assignment box, browse to find the workbook for Lab 9.
6. Select "Lab 9" for the assignment and then click "Upload".
7. Double check to make sure the file has been uploaded.
8. Click "Sign Off" near the top right hand corner of the window.

Due date:

Thursday, Nov. 16. There will be a 24 hour grace period. After the grace period late submittals will not be accepted except with written permission from the instructor and will be subject to a 20% per day penalty. (Late assignments turned in over 24 hours after the due date are 2 days late and are subject to a 40% penalty.)

lab09.html, 11/10/06