Researchers at the Cornell University Food and Brand Lab conducted an experiment

Question

Researchers at the Cornell University Food and Brand Lab conducted an experiment at a fitness camp for adolescents (Wansink & van Ittersum, 2003). Campers were given either a 22-ounce glass that was tall and thin or a 22-ounce glass that was short and wide. Campers with the short glasses tended to pour more soda, milk, or juice than campers with the tall glasses.

a. Is it likely that the researchers used random selection? Explain.

b. Is it likely that the researchers used random assignment? Explain.

c. What is the independent variable, and what are its levels?

d. What is the dependent variable?

e. What hypothesis test would the researchers use? Explain.

f. Conduct step 1 of hypothesis testing.

g. Conduct step 2 of hypothesis testing.

h. How could the researchers redesign this study so that they could use a paired-samples t test?

i. Obesity than other California schools. Describe the flaw in this argument by discussing the importance of random selection and random assignment.

Explanation / Answer

a: It is LESS likely that the researchers used a random selection.

Reason: Only those who volunteered for the fitness camp, became a part of the experiment. The population from which the sampe is drawn is not clearly defined.

b: Definitely yes, the researchers assigned the campers different sized glasses randomly. Hence the assignment of glasses was a pure random assignment.

c. The independent variable is the "size of the glass".

It is termed as independent because , we are free to vary the size , and observe its effect on the health of adolscents.

Since there are two variants in size "22 ounce tall & thin glass" & "22 ounce short & wide glass", hence the level of independent variable is "two"

d. Dependent variable: No clear specification is made regarding what is being observed in the given experiment. It is more likely to be the obseity level in adolscents due to the flow level of liquids using the 22-ounce glass. Or in simpler terms we can consider the dependent variable to be "impact on health".

e. Step I of hypothesis Testing:

Frame the hypothesis:

Null hypothesis: There is no impact of glass size on the health level of adolscents

Alternate Hypothesis: The size of glass has an impact on the health of adolscents

f. Step 2 of Hypothesis testing is to set the significance level. The most common values of significance levels used are 0.05 and 0.01. For more precise and accurate result set a higher value of significance level.

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