Missed Pretest 2 Questions Flashcards
What is the random variable of the sampling distribution x bar?
the sample mean
Fill in the blank: Central Limit Theorem allows us to compute probabilities about ___________ using the standard Normal table provided the sample size of the random sample is sufficiently large.
x bar
Standard error of x̄ refers to
the estimate of the standard deviation of the sampling distribution of x̄.
The test statistic measures
how many standard errors the observed x̄ is from the claimed parameter value μ0.
Twelve runners were randomly sampled and asked to run a 10-kilometer race. Their times are recorded in the following stemplot. On the basis of the following stemplot, is use of a one-sample t confidence interval procedure to estimate the mean time appropriate?
1 | 1 1
2 | 2 2 2
3 | 3 3 3
4 | 4 4
5 | 5 5
Yes, because the runners were randomly sampled and there are no serious outliers in the stemplot.
Suppose you are testing the following hypotheses. What is the type I error for these hypotheses? H0 : Cake is not done, versus Ha: Cake is done
To believe that the cake is done when it is still not done.
The weekly oral dosage of anabolic steroids was measured on a sample of 20 body builders. A 95% confidence interval estimate for the average weekly oral dose of anabolic steroids obtained from these results was 152 mg to 194 mg. Which one of the following is a correct interpretation of this confidence interval?
We are 95% confident that the average weekly dose of anabolic steroids used by all body builders is between 152 mg. and 194 mg.
Referring to question 40, the mean of the sample is 173 mg and the margin of error for the confidence interval given in the above question is 21 mg. Which one of the following is a correct interpretation of margin of error?
The maximum difference we expect between our sample result and the true average weekly oral dose is no more than 21 mg.
Suppose we have H0 : μ = 30 versus Ha : μ > 30 with p-value = .032. If we decided to test H0 : μ = 30 versus Ha: μ ≠ 30, what is the p-value for this new Ha assuming all other factors are the same?
.064
Which one of the following is NOT part of the definition for p-value?
A. Probability that the null hypothesis is true.
B. Probability of obtaining a value of the statistic.
C. The value of the statistic is farther from the claimed parameter value than the observed statistic.
D. The null hypothesis is assumed to be true.
Probability that the null hypothesis is true.
Which one of the following is NOT a correct statement about margin of error?
A. A small margin of error says that we have pinned down the parameter quite precisely.
B. For fixed level of confidence, increasing the sample size, n, reduces the margin of error.
C. For fixed sample size, decreasing level of confidence increases the margin of error.
D. To obtain a smaller margin of error without increasing sample size, you must be willing to accept lower confidence.
For fixed sample size, decreasing level of confidence increases the margin of error.
The null hypothesis is a statement of
no effect or no change in the population parameter.
All of the following are true statements about the p-value except one. Which statement is false?
A. P-value is the area in the tail of the sampling distribution defined by H0.
B. The smaller the p-value, the greater the evidence for the alternative hypothesis.
C. The larger the p-value, the greater the agreement between the data and H0.
D. P-value is used to determine the significance level.
P-value is used to determine the significance level.
Tests of significance on μ and confidence intervals for μ (with σ known) are based on
the sampling distribution of x̄.
The shape of the histogram of sample data gets closer to the shape of the Normal distribution as the sample size increases.
False
