"Hope here for the poor to move up in life" by Janice Heng, The Straits Times Singapore, January 13, 2012, Prime News Section. Document source: LexisNexis. (Sign in via the Colgate portal.) Generally, search for the author's name, the publication, and an important word or two from the title. You can search the Lexis-Nexis Academic database from off-campus by approaching it through the Colgate University library website, but you will be required to provide your Colgate username and password.Possible essay questions:
- Is a low correlation coefficient the right statistic to be measure social mobility? How might the fraction of people born into a certain income level who reach a different income level be used instead?
- Describe the reasons given in the article for why social mobility might have decreased for those born (in Singapore) more recently.
Computer project:
Boy Scouts and Girl Scouts are taught that a way to measure temperature is by counting cricket chirps and applying a formula to find the temperature. The data in the following reference gives the number of cricket chirps in a 15-second period and the temperature in degrees Farenheit at that time: Data on cricket chirps vs. temperature.Excel instructions for finding the SD-line and regression line can be found in the supplement Using Excel 2: Slope and Intercept of Regression Lines
- Copy the data above into a spreadsheet program, with the numbers of chirps in a 15-second period in the left column and the temperatures in the right column.
- Create a scatter plot for the data. Put Chirps per Period on the horizontal axis and Temperature on the vertical axis.
- In a sentence or two, describe the association that exists between the two variables. What type of association (linear, curvilinear or none? positive or negative?) is present? How strong is the association? (Type this into your spreadsheet so that it will come out when you print.)
- Have the spreadsheet compute the averages and standard deviations of each variable and the correlation coefficient between them. (See the link below for help in getting this data from Excel.) Create a third column that contains "Temperature" values on the SD-line for each Chirps value.
- Have Excel compute the slope and y-intercept of the regression line for Temperature on Chirps per Period. Label these values appropriately.
- Create a fourth column to hold a list of "predicted" Temperature values lying on the regression line.
- Create a second scatter diagram of the data that includes plots of the SD-line and the regression line for Temperature vs Chirps per Period. Change the style for the data points that represent the lines to actual lines (double-click on the data point and turn on lines and turn off markers).
- Which is steeper, the SD-line or the regression line? Does this make sense? Why?
Last revised 20 January 2012. Mail to dlantz@colgate.edu
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