Spring 2006 10 POINTS
TCSIG 330 DESCRIPTIVE STATISTIC/EXCEL ASSIGNMENT 2
The purpose of this assignment is to provide practice making scatterplots and calculating and interpreting the Pearson Product Moment Correlation Coefficient.
Due Date: At the beginning of lecture Monday, April 17. Late papers will be accepted with the loss of 3 points during class on Wednesday, April 19. Late papers will be accepted with the loss of 5 points any time after lecture on Wednesday, February 1. Papers will not be accepted after Monday, April 24.
Background Reading: (1) SMARTPsych Excel tutorial Working with Data, and (2) Textbook Chapter 9.
See the Web Page below for help understanding the way scatterplots “map” to the Pearson Product Correlation and the influence of number of participants. Use the new sample button to see different examples.
Data for the assignment (fabricated for the purposes of this assignment):
The table contains the participant number, the number of roommates each participant has, the number of hours each participant spends in conflict over division of chores per month, and the participant's GPA.
Partic No. / Conflict / Rmates / GPA1 / 2 / 1 / 4.0
2 / 2 / 2 / 3.2
3 / 4 / 3 / 2.3
4 / 0 / 1 / 3.3
5 / 4 / 5 / 2.3
6 / 3 / 3 / 2.9
7 / 2 / 3 / 3.0
8 / 0 / 0 / 4.0
9 / 1 / 2 / 3.3
10 / 5 / 5 / 1.8
11 / 5 / 4 / 0.7
12 / 2 / 2 / 3.4
13 / 4 / 3 / 2.2
14 / 7 / 3 / 1.7
15 / 1 / 1 / 3.3
16 / 4 / 4 / 1.9
Spring 2006 10 POINTS
THERE ARE THREE PARTS TO THE ASSIGNMENT
PART 1: HAND DRAW A SCATTERPLOT (1 point) Use the attached worksheet page to draw a scatterplot for number of roommates versus hours of conflict. Put number of roommates on the y-axis and hours of conflict on the x-axis. Scale and label the axes appropriately. You may use graph paper if you prefer.
PART 2: EXCEL ANALYSIS (7 points)
1. Enter the data in an Excel spreadsheet. Use Excel to calculate the means and standard deviations for the three variables. Round means and std dev. to two decimal places.
2. Use Excel to make two scatterplots. In one put number roommates on the y-axis and hours of conflict per week on the x-axis. In the other put GPA on the y-axis and number of roommates on the x-axis. Label the axes with the variable names and ENTER YOUR FIRST AND LAST NAME and STUDENT NUMBER IN THE TITLES. Be sure to check that your figures are scaled appropriately.
3. Use Excel (PEARSON) to calculate the Pearson Product Moment correlation coefficients between
a. Hours of conflict per week and number of roommates
b. Number of roommates and GPA
c. Hours of conflict per week and GPA
Label the correlations so I know which one is which.Round your answer to two decimal places.
PART 3: REPORTING CORRELATIONAL RESULTS (2 points)
1. Write two sentences into the spreadsheet: one that reports the correlation results for hours of conflict with number of roommates and another that describes the association between the two variables.
2. Write two sentences into the spreadsheet that report the correlation results for hours of conflict with GPA and describes the association between these two variables.
**MAJOR HINT ON WRITING SENTENCES ABOUT THE RESULTS.**
The word CAUSE and the word PROVE should NOT appear anywhere!
Assignment preparation:
Attach a cover page with your name and student number. A cover sheet helps me keep track of assignments and grades. Put your work together in the order noted above: the cover page, Part 1 (the hand-drawn scatterplot), then the Part 2 and Part 3 excel printout.
You will probably find it easier to fit Part 2 and Part 3 together on one page if you use landscape orientation for printing (but not required).
PLEASE HAND WRITE YOUR NAME ON EVERY PAGE (to help me if the pages separate). Staple everything together or even better - clip the pages together with a sturdy black clip.
Spring 2006 10 POINTS
Getting Help
You are encouraged to talk about the assignment with others - including me, your classmates, and any consultants in the computer labs. However, the hand-drawn scatterplot, Excel work, and written descriptions of the correlations must be your own. Sharing files and copying is not acceptable. YOU MUST HAVE YOUR NAME ENTERED IN EXCEL IN THE TITLE of each scatterplot to RECEIVE CREDIT FOR YOUR WORK IN EXCEL.
THOUGHT QUESTIONS (DO NOT turn in this answer)
How much do outliers matter? Recall that an outlier is a data point that lies well outside the distribution of scores. In Excel, play around with the data points to see how your changes influence the Pearson Product Moment Correlation Coefficient and the way that the scatterplot looks. A nice feature of excel is that changing the data point will “simultaneously” change the mean, correlations, and scatterplots so you can observe the influence of your change directly.
Spring 2006 10 POINTS
NAME ______Student Number______
PART 1: HAND DRAW A SCATTERPLOT FOR DATA SET 1 (1 point) Put number of roommates on the y-axis and hours of conflict on the x-axis. Scale and label the axes appropriately.