1- A researcher calculated the mean difference between two varieties of corn of
ID: 3321988 • Letter: 1
Question
1- A researcher calculated the mean difference between two varieties of corn of 10.3 bu/ac with an upper confidence limit of 12.3 bu/ac and a lower confidence limit of 8.3 bu/ac using a significance level () of 0.1. Which of the following do we know? Mark all that are correct.
a. The difference would be declared statistically different at =0.1.
b. The difference would not be declared statistically different at =0.1.
c. The true difference between the two varieties will be between 8.3 bu/ac and 12.3 bu/ac 90% of the time.
d. This is an economically important differenc
2. In one issue of a highly reputable journal, results from a study indicated that polyphenolic compounds increased in organic grown tomatoes compared to conventionally grown tomatoes. In the next issue, a published study indicated no detectable differences in polyphenolic compounds between the two methods of production. From a statistical viewpoint, what is a possible explanation? Circle all that are possible explanations of the discrepancy.
a. A type I error occurred in the first study.
b. A type I error occurred in the second study.
c. A type II error occurred in the second study.
d. Uncontrolled differences existed between the two studies that could have affected the results.
Neither a or b
3. If we plan to use one-way anova to analyze the results of an experiment, which of the following must be true to satisfy the randomization requirement?
a-The number of observations must be chosen randomly
b- The number of groups must be chose randomly
c-The independent variable is chosen randomly
d- The experimental units must be randomly assigned to treatments.
5. In a one-way Anova, if SSerror decreases while the other sums of squares and degrees of freedom stay the same, then
The value of the test statistic increases
The p-vale decreases
Both a and b
Neither a nor b
6-In one-way ANOVA, SStotal measures
a- The overall variability in the data
b-The variability within groups
c-The variability among groups
d-The variability of the response variable values around their group sample means
e- The variability of the group sample means around the overall mean.
Explanation / Answer
1. b and c are correct
Note: b is correct as the confidence interval doesn’t include zero
2. d is correct
3. d is correct
5. Both a and b
As sse decreases test statistic increases ( as mse decreases , which is in the denominator)
As test statistic increases, p decreases
6. a is correct
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