QUESTION #1 (4 marks total)
You are interested in sampling 1,000 residents living in Yarmouth to determine their opinion
about the quality of their drinking water. The population of Yarmouth is 50,000 with 10,000
getting water from private wells and 40,000 getting “town water”. What would be the
composition of your sample of 1,000 residents and how would you choose it, if you used
stratified sampling? Show your work.
QUESTION #2 (7 marks total)
Suppose you want to test whether an energy drink called “Zap” improves math performance
in York’s Psyc 2030 students. You also want to determine whether there’s a difference in math
performance because of their already-existing experience with Zap. More specifically, is math
performance better for students who are habitual Zap drinkers (drink it every day) compared to
students who never drank Zap before? Students in each of these two groups are randomly
assigned to one of three Zap dosage levels: 0oz, 5oz, or 10oz.
2A) How many different conditions are in the study?
2B) What would the control group be?
2C) What is the name given to this type of design?
2D) Must subjects be randomly assigned to all of the different conditions? Briefly explain
2E) Can one infer a cause-and-effect relationship in this study? Briefly explain.
QUESTION #3 (12 marks total)
3A) If you wanted to determine whether there is a relationship between “amount of Zap
consumed” and “IQ” and decided to use the correlation method of research, what might you do?
3B) If you find that these two variables are strongly correlated can you infer a cause and effect
relationship? Why? What might be acting as the cause?
3C) Give one variable that would likely be positively correlated with the consumption of Zap in
3D) Give one variable that would likely be negatively correlated with the consumption of Zap
in university students. (Don’t use the same variables as in 3C)
3E) If the correlation coefficient between Zap consumption and IQ is r = -.86, fully describe how
these two variables are related.
3F) Calculate the coefficient of determination. What is it telling you about the relationship
between these two variables? (Be sure to use the terms “IQ” and “amount of Zap consumed” in
QUESTION #4 (14 marks total)
4) A researcher is interested in the effects of room color (yellow, blue) and room temperature
(20, 24, 28 degrees Celsius) on happiness. A total of 120 university students participated in this
study, with 20 students randomly assigned to each condition. After sitting for 30 mins. in a room
that was painted either yellow or blue, and that was either 20, 24, or 28 degrees, students were
asked to rate how happy they felt on a scale of 1 to 15, where 15 represented the most happiness.
The results are as follows:
temperature room color happiness
20 yellow 12
24 yellow 10
28 yellow 6
20 blue 4
24 blue 4
28 blue 4
4A) Place the data into the cells of the matrix and determine the row and column means (a handdrawn matrix is fine).
4B) Draw a fully labeled line graph of the results (a hand-drawn graph is fine).
4C) List each significant effect and after each one, describe what the effect is telling us about
how temperature and color affected happiness. (For the purpose of this exercise, assume that a
difference of “1” between any of the row or column means is a significant difference. Also, if
the data or graph seem to indicate an interaction effect, consider it as being a significant
4D) If any of the above effects should take precedence, indicate which effect(s). (If they are of
equal importance, simply indicate so.)
4E) What is the name given to this type of design?
QUESTION #1 (4 marks total)