Homework #3
Chi-Square and t-Tests in SPSS
Having
grown tired of working with rats, a group of ambitious researchers genetically
engineered super-hamsters. They discovered a way to create hamsters in
all colors of the rainbow. Taking a subsample of 40 colorful hamsters
(red, yellow, green, and blue), the researchers randomly assigned the hamsters
to a treatment or control group. The treatment group had a
bioluminescence gene added to their DNA sequence, which caused them to glow in
the dark. The researchers hypothesized that this would affect the
hamster’s self-esteem, such that the glowing hamsters would exhibit more
self-confidence due to their fantastic appearance, and thus would complete a
maze faster than hamsters who could not bioluminesce. Prior to the "big
race", the researchers gave the hamsters some practice runs in the maze (round1
and round2) where scores represent how long it took the hamsters to
successfully complete the running of the maze. The data file
"hamsterdata.sav" contains 7 variables:
ID – identification numbers assigned to the
hamsters
Treat – Treatment = 1/Control = 0 assignment
Color – red, yellow, green, or blue
Weight – Hamster’s weight in ounces
Time – time to complete the maze in the "big
race"
round1 - time to complete the maze in the first
practice run
round2 - time to complete the maze in the second
practice run
1. Your first hypothesis has to do with whether
hamsters of each color occur with equal frequency. Test this hypothesis
using a Univariate Chi-Square test to determine if certain colors are more
common than others. What do the results indicate? Report the results in APA
style and also interpret the results in terms of what this means for color
frequencies.
2. When the researchers were deciding which
hamsters to give the special bioluminescent gene to, did they discriminate
based on color? If they did, there should be a significant association
between treat and color. Test this hypothesis by conducting
a Bivariate Chi-Square test. Was there a significant association? Report the
results in APA style and also interpret the results in terms of the
relationship between the two variables.
3. Your next research question involves the
variable weight. You know that in the population, the average
hamster weight (µ) = 4 ounces. Test the hypothesis that the average weight
in this sample of hamsters is different than the population average of 4 ounces
using a Single Sample t-Test. What do you conclude? Report the results in
APA style. Are these hamsters generally heavier, lighter, or the same weight as
average-sized hamsters?
4. Does the addition of the bioluminescent gene
really increase hamster self-esteem, thus making them complete the maze
faster? Using treat as your grouping variable, conduct an
Independent Samples t-Test on time. Report the results in APA
style. What do you conclude about the effect of the gene on time?
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