(1) If possible, contact your school’s Office of Institutional Research or Registrar to get statistics about the student population. These statistics may also be available online. It should not be difficult to get a series of characteristics about the population: gender, class, race/ethnicity, major, residence (on/off campus), and so on. Assign a group of students to each statistic. Ask them to design their own way to measure their characteristic (they may want to refer to Chapter 4). Assign each group to record the characteristics for every other member in your class (you will have to provide a list of students in your class). Have them tally up their results and decide if your class is representative of the larger student population. Ask them to explain how this would affect the generalizability of any research done in this class to the student population. What other characteristics that were not measured may lead to bias in the sample?
(2) Modifying or adding on to the first exercise (above), ask each individual in each group of students to gather data about 10 students outside of class and return to the next class period. This will yield a sample size 10 times larger than the in-class sample. Again, tally up the results and decide if additional availability sampling approaches representativeness of the population. Ask students to explain why asking 10 times as many students improves representativeness (it should!) but is still unreliable.
(3) For this project, you and a partner will need to locate a daily newspaper that contains a large number of employment, housing, or car classified advertisements (at least 100). Plan to draw a random sample of 25 advertisements.
(a) Identify the pages on which the employment, car, house, or rental ads appear.
(b) Make copies of the pages and distribute them to each member of the pair. After this step (until Step 9), individuals in the pair should work separately.
(c) Number each ad consecutively. Note the total number of ads.
(d) Using your random numbers table, determine the number of digits that you will need in your numbers to identify cases in your “population” of ads. (e.g., if there are 152 ads, you will need to use three digit numbers.) Decide on a rule for selecting numbers in the table, such as every number as you move from right to left across a row and then from left to right back across the next row. Close your eyes and pick a starting point. Following your selection rule, write down the first 25 numbers that you encounter that you encounter that fall within the range of ad numbers (if there are 152 ads, this means you should write down the first 25 numbers between 1 and 152).
(e) Circle the ads corresponding to the numbers you have written down from the random number table.
(f) Record one or two characteristics of each ad. These might be the type of job advertised, the community where a house or apartment is located, whether the asking price is listed, or the asking price itself.
(g) If you used types of jobs or communities as a characteristic, review these types and, if it seems warranted, group them together in a more limited number of categories (e.g., white collar and blue collar, or north side and south side).
(h) Now tally up the characteristics (for example, how many housing ads listed an asking price and how many didn’t?) Calculate an arithmetic average for the prices or salaries you recorded (add up all the prices or salaries and then divide by the total number of prices or salaries listed.) These are your sample statistics.
(i) Compare your sample statistics with those of your partner.
(j) Write a brief statement together in which you discuss the similarity or dissimilarity of your samples and whether you think your samples accurately reflect the population of ads.
(4) For this project, you will need to secure a copy of the most recent directory of faculty members at your school. If at all possible, make photocopies of the relevant pages so you can write on them. Directories are often available in academic departments, the library, and on websites.
(a) Go through the directory and cross listings that are not specific faculty members (e.g., “President’s Office” or “Graduate Office,” etc.).
(b) Count the number of remaining elements. This is your population (all faculty members listed in the most recent directory, NOT all employees).
(c) Designate a sampling interval in which you will end up with a sample of 25 individuals. (This can be figured by dividing the total number of elements in the population by 25).
(d) Randomly select a starting point in the directory, preferably through use of a random number table.
(e) Write down every nth name from the directory and his or her department or other affiliation (where n = the sampling interval designated in #3 above).
(f) After you have written down the names and departments for each member of your sample, compile summary statements about the same in terms of gender of faculty member and department (you may need to condense departments, such as “Social and Behavioral Sciences,” “Natural Sciences,” “Not Academic Department,” and so on.
(g) Write a brief statement describing the findings about the population based on the sample.
(h) (Steps 8 and 9 are an additional exercise.)
(i) Contact the people selected for your sample, explain that you are doing a class exercise on sampling procedures and that you have selected them as part of your sample. Ask them a predetermined question of some interest or relevance (but make the questions short, easy to answer, and relevant, such as When did you receive your highest degree and/or from where did you receive it?).
(j) Write a brief essay about this research, in which you describe your sampling technique and your findings.
Individual and Group Activities
(1) Ask students to: Check out the “people and households” section of the U.S. Census Bureau website: www.census.gov. Based on some of the data you find there, write a brief summary of some aspects of the current characteristics of the U.S. population.
(2) Provide students with the following instructions: The Pew Research Center explains their sampling methods here: http://www.pewresearch.org/methodology/u-s-survey-research/sampling/. This report focuses on six issues in sampling. Choose one and write a short summary on the issue you chose.