Download Goodness of Fit/Analysis of Variance

Goodness of Fit/Analysis of Variance
Worksheet 23
1. For a dihybrid cross, if the assortment is independent, we expect the odds of the 4 phenotypes to be
9:3:3:1
for respectively,
both dominant: dominant, recessive: recessive, dominant: both recessive
traits expressed.
(a) Give the probabilities for each of the four phenotypes.
(b) Give a table of the expected number of observations for 3840 total observations
both dominant
dominant, recessive
recessive, dominant
both recessive
(c) Data from classic experiment with Starchy/sugary and Green/white seedlings, progeny of 3840
self-fertilized heterozygotes is
both dominant
1998
dominant, recessive
906
recessive, dominant
904
both recessive
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Compute the value of the chi-square statistic.
(d) Estimate the p-value and give your conclusion for a goodness of fit hypothesis test.
2. In a 2011 study from Texas A & M University, forty-two drivers were placed behind the wheel of a car
and drove around a closed track about 11 miles in length. The researchers monitored how long it took
drivers to react to a flashing light while driving normally and while attempting to text or to read a
message on a mobile phone. Here is a summary of the data.
conditions
control
texting
reading
# observations
42
42
42
mean
1.754
4.302
3.278
standard
deviation
0.806
1.614
1.274
(a) Give the appropriate hypothesis for this situation.
(b) Determine the value of the F statistic for a one way analysis of variance.
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(c) What are the degrees of freedom appropriate with this test.
(d) Give the p-value for the test. What are you conclusions.
(e) Give a 95% confidence interval for the difference in mean reaction times between texting and
control and between reading and control.
(f) Give a hypothesis for the contrast that compares the control to the average of the mean times for
texting and writing.
(g) Give the value of the t statistic for this test. What are the degrees of freedom?
(h) Do you reject this hypothesis. Explain your answer.
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