problem library

A researcher posed a null hypothesis that there was no significant difference between boys and girls on a standard memory test. He randomly sampled 100 girls and 100 boys in a community and gave them the standard memory test. The mean score for girls was 70 and the standard deviation of mean was...

A researcher posed a null hypothesis that there was no significant difference between boys and girls on a standard memory test. He randomly sampled 100 girls and 120 boys in a community and gave them the standard memory test. The mean score for girls was 70 and the standard deviation of mean was...

In order to test if there is a difference between means from two populations, which of following assumptions are NOT required? a. The dependent variable scores must be a continuous quantitative variable. b. The scores in the populations are normally distributed. c. Each value is sampled...

Compared to the normal distribution, the t distribution has ___ values at the top and ___ at the tails. a. More; less b. More; more c. Less; less d. Less; more d. Less; more t value chart is wider and flatter

Imagine a researcher posed a null hypothesis that in a certain community, the average energy expenditure should be 2,100 calories per day. He randomly sampled 100 people in that community. After he computed the t value by calculating a two-tailed t-statistic, he found that the probability value...

Imagine that a researcher wanted to know the average weight of 5th grade boys in a high school. He randomly sampled 5 boys from that high school. Their weights were: 120 lbs., 99 lbs, 101 lbs, 87 lbs, 140 lbs. The researcher posed a null hypothesis that the average weight for boys in that high...

Imagine that a researcher wanted to know the average weight of 5th grade boys in a high school. He randomly sampled 5 boys from that high school. Their weights were: 120 lbs., 99 lbs, 101 lbs, 87 lbs, 140 lbs. What's the standard error of the mean? 9.29839 using our statistics calculator

Imagine that a researcher wanted to know the average weight of 5th grade boys in a high school. He randomly sampled 5 boys from that high school. Their weights were: 120 lbs., 99 lbs, 101 lbs, 87 lbs, 140 lbs. What's the sample standard deviation? 20.79182532 using stdev.s in excel or also...

Which of the following descriptions of null hypothesis are correct? (Select all that apply) a. A null hypothesis is a hypothesis tested in significance testing. b. The parameter of a null hypothesis is commonly 0. c. The aim of all research is to prove the null hypothesis is true d...

Power is equal to: a. α b. β c. 1 - α d. 1 - β d. 1 - β Correct Decision 1 - β = Power of a Test

If a statistical test result is not significant at the 0.05 level, then we can conclude: a. It is not significant at 0.01 level b. It is not significant at 0.10 level c. It must be significant at 0.01 level d. It must be significant above 0.05 level b. It is not significant at 0.10 level As...

Which of the following descriptions of confidence interval is correct? (Select all that apply) a. If a 99% confidence interval contains 0, then the 95% confidence interval contains 0 b. If a 95% confidence interval contains 0, then the 99% confidence interval contains 0 c. If a 99% confidence...

A teacher assumed that the average of grades for a math test was 80. Imagine 20 students took the test and the 95% confidence interval of grades was (83, 90). Can you reject the teacher's assumption? a. Yes b. No c. We cannot tell from the given information a. Yes At the 0.05 significance...

If the P-value of a hypothesis test is 0.40, you conclude a. You accept the null hypothesis b. You reject the null hypothesis c. You failed to reject the null hypothesis d. You think there is a significant difference c. You failed to reject the null hypothesis due to a high p value...

A student posed a null hypothesis that during the month of September, the mean daily temperature of Boston was the same as the mean daily temperature of New York. His alternative hypothesis was that mean temperatures in these two cities were different. He found the P value of his null hypothesis...

When you conduct a hypothesis testing, at which of the following P-value, you feel more confident to reject the null hypothesis? a. 0.05 b. 0.01 c. 0.95 d. 0.03 b. 0.01 The lower the p value, the more confident you are about rejecting the null hypothesis.

A student hypothesized that girls in his class had the same blood pressure levels as boys. The probability value for his null hypothesis was 0.15. So he concluded that the blood pressures of the girls were higher than boys'. Which kind of mistake did he make? a. Type I error b. Type II error...

___is the probability of a Type II error; and ___ is the probability of correctly rejecting a false null hypothesis. a. 1 - β; β b. β; 1 - β; c. α; β; d. β; α b. β; 1 - β; H0 is true = Correct Decision 1 - α Confidence Level = Size of a Test α = Type I Error Ho is false = Type II Error β...

Which of the following could reduce the rate of Type I error? a. Making the significant level from 0.01 to 0.05 b. Making the significant level from 0.05 to 0.01 c. Increase the Β level d. Increase the power a. Making the significant level from 0.01 to 0.05 This widens the space under...

A teacher hypothesized that in her class, grades of girls on a chemistry test were the same as grades of boys. If the probability value of her null hypothesis was 0.56, it suggested: a. We failed to reject the null hypothesis b. Boys' grades were higher than girls' grades c. Girls' grades were...