Question 1

Form a conclusion about statistical significance. Do not make any formal calculations. Either use the results provided or make subjective judgments about the results.
-A researcher investigated whether following a vegetarian diet could help to reduce blood pressure. For a sample of 85 people who followed a vegetarian diet for 4 months, the mean systolic blood pressure was 124 mmHg and for a sample of 75 people who followed a nonvegetarian diet for 4 months, the mean systolic blood pressure was 138 mmHg.
Methods of statistics show that if a vegetarian diet had no effect on blood pressure, there would be less than 1 chance in a 100 of getting these results. Does the result have statistical significance? Why or why not? Does the result have practical significance?

Accepted Answer

The answer of Form a conclusion about statistical significance. Do...

Question 2

Define continuous and discrete data and give an example of each.

Accepted Answer

The answer of Define continuous and discrete data and give...

Question 3

Define sampling error and nonsampling error. Give examples of nonsampling error.

Accepted Answer

The answer of Define sampling error and nonsampling error. Give...

Question 4

Explain the difference between stratified and cluster sampling.

Accepted Answer

The answer of Explain the difference between stratified and cluster...

Question 5

Why do you think that cluster sampling is frequently used in practice.

Accepted Answer

The answer of Why do you think that cluster sampling...

Question 6

Would an observational study or an experiment be more appropriate to investigate the effects on humans of a substance known to be toxic? Explain.

Accepted Answer

The answer of Would an observational study or an experiment...

Question 7

Use critical thinking to determine whether the sampling method appears to be sound or is flawed.
-"7 out of 10 dentists recommend Brand X toothpaste". This finding is based on the results of a survey of 10 randomly selected dentists. What is wrong with this survey?

Accepted Answer

The answer of Use critical thinking to determine whether the...

Question 8

A market researcher obtains a sample of 50 people by standing outside a store and asking every 20th person who enters the store to fill out a survey until she has 50 people. What sampling method is being used here? Will the resulting sample be a random sample? Will it be a simple random sample? Explain your thinking.

Accepted Answer

The answer of A market researcher obtains a sample of...

Question 9

A group of men aged 50-59 followed a strict exercise regime for one year. The mean reduction in systolic blood pressure at the end of the year was 2.7 mmHg. Methods of statistics were used to determine that if the exercise regime had no effect on blood pressure, the likelihood of seeing this reduction in blood pressure by chance would be less than 1 in 100. Do the results have statistical significance? Do they have practical significance? Explain.

Accepted Answer

The answer of A group of men aged 50-59 followed...

Question 10

Use critical thinking to develop an alternative conclusion.
-In a study of headache patients, every one of the study subjects with a headache was found to be improved after taking a week off of work. Conclusion: Taking time off work cures headaches.

Accepted Answer

The answer of Use critical thinking to develop an alternative...

Question 11

Does systematic sampling result in a random sample? Why or why not?

Accepted Answer

The answer of Does systematic sampling result in a random...

Question 12

A manufacturer of laptop computers claims that only 1% of their computers are defective. In a sample of 600 computers, it was found that 3% were defective. If the proportion of defectives were really only 1%, there would be less than 1 chance in 1000 of getting such a large proportion of defective laptops in the sample. Is there statistically significant evidence against the manufacturer's claim? Why or why not?

Accepted Answer

The answer of A manufacturer of laptop computers claims that...

Question 13

Use critical thinking to develop an alternative conclusion.
-A study of achievement scores by sixth-grade students on a standardized math test showed the three top scorers were all gifted piano players. Conclusion: Playing the piano leads to mathematical achievement.

Accepted Answer

The answer of Use critical thinking to develop an alternative...

Question 14

Use critical thinking to determine whether the sampling method appears to be sound or is flawed.
-"38% of adults in the United States regularly visit a doctor". This conclusion was reached by a college student after she had questioned 520 randomly selected members of her college. What is wrong with her survey?

Accepted Answer

The answer of Use critical thinking to determine whether the...

Question 15

At a school there are two different math classes of the same age. The two classes have different teachers. The school principal is interested in gauging the effectiveness of two different teaching methods and asks each teacher to try one of the methods. At the end of the semester both classes are given the same test and the results are compared. In this experiment, what is the variable of interest? Give some examples of variables which could be confounding variables.

Accepted Answer

The answer of At a school there are two different...

Question 16

A researcher wants to obtain a sample of 100 school teachers from the 800 school teachers in a school district. Describe procedures for obtaining a sample of each type: random, systematic, convenience, stratified, cluster.

Accepted Answer

The answer of A researcher wants to obtain a sample...

Question 17

Define and give examples for nominal, ordinal, interval, and ratio levels of measurement. Describe the type of statistics which might be reported for each.

Accepted Answer

The answer of Define and give examples for nominal, ordinal,...

Question 18

Form a conclusion about statistical significance. Do not make any formal calculations. Either use the results provided or make subjective judgments about the results.
-Charlie's teacher claims that he does not study and just guesses on exams. On an exam with 201 true-false questions, Charlie answered 53.7% of the questions correctly.
Calculations using these results show that if he were really just guessing, there would be roughly 1 chance in 7 that he would do this well. Is there statistically significant evidence against the teacher's claim that Charlie is just guessing? Why or why not?

Accepted Answer

The answer of Form a conclusion about statistical significance. Do...

Question 19

A lawyer surveyed a simple random sample of his colleagues and asked them whether they were left-handed or right-handed. Is this convenience sample likely to provide results typical of all adults in the United States? Do convenience samples in general provide good results?

Accepted Answer

The answer of A lawyer surveyed a simple random sample...

Question 20

A researcher obtains a sample of high school teachers in his school district by randomly selecting 10 high schools and interviewing all the teachers at each of these 10 schools.
What kind of sampling is being used here? Will the resulting sample be a simple random sample of the population of teachers in the school district? Explain your thinking.

Accepted Answer

The answer of A researcher obtains a sample of high...

Quiz 1: Introduction to Statistics