FINAL (recycled questions from exams 1-3)

A survey asks people to rate their agreement with a statement using the following options: strongly disagree, disagree, neutral, agree, strongly agree. What scale is being used to measure agreement in this case?

Ordinal

For the following population of scores: 9, 9, 5, 8, 8, 9, what is the value of SS?

12

Which of the following best describes the goal of using a confidence interval?

Estimating a population parameter using sample data.

Although a research study typically examines a , research questions typically are about a .

sample;population

For the four scores: X = {1, 4, 6, 7}, what is the value of ΣX2 ?

102 (square before adding)

Answer questions 19-28 based on this description of a study: A researcher wants to determine whether habitual criminals exhibit greater psychopathy than seen in the general population. To test this, the researcher obtains a random sample of n = 25 habitual criminals and administers a psychopathy test. The 25 criminals produce a mean score of 54.4. In the general population, psychopathy is normally distributed with μ = 50 and σ = 10. Do habitual criminals exhibit greater psychopathy than the general population? What is the critical value of the test statistic, assuming α = .05 and a one-tailed test?

+ 1.64

Answer questions 14-21 based on this description of a study: A college dean wanted to answer the question of whether living off-campus (n=14) is associated with lower grades. To test this belief, the dean obtained a random sample of students living on campus (n=16) and looked up their GPAs. Among, those living on-campus, the mean GPA was 2.9 with SS = 0.6. Among those living off-campus, the mean GPA was 2.7 with SS = 0.8. Assume that the dean wants to do a hypothesis test to answer of interest. What is the critical value for t, assuming a one-tailed test with alpha = .05?

+1.701

If a normally-distributed population has μ = 80, σ = 12, what is the probability of obtaining a sample mean between 78 and 82 for a random sample with n = 9 scores?

.3830

Illumination Bulb Company makes a 60-watt light bulb that they've tested extensively and know that the bulbs last μ = 1100 hours, with σ = 100. The distribution of the life of the bulbs is normal. What is the probability that one randomly selected bulb will last less than 1150 hours?

.6915

If an entire population with μ = 60 and σ = 8 is transformed into z-scores, then the distribution of z-scores will have a mean of ___ and a standard deviation of ___.

0 and 1

On average, what value is expected for the F-ratio if the null hypothesis is true?

1

For the following population of scores: 9, 9, 5, 8, 8, 9, what is the standard deviation?

1.41

For the four scores:X={1,4,6,7},what is the value ofΣ(X-1)?

14 (subtract 1 from each then add)

For the following population of scores: 9, 9, 5, 8, 8, 9, what is the variance?

2

If a researcher does a two-tailed test using z and sets alpha = .04, which of the following is the critical value for z?

2.05

Answer questions 19-28 based on this description of a study: A researcher wants to determine whether habitual criminals exhibit greater psychopathy than seen in the general population. To test this, the researcher obtains a random sample of n = 25 habitual criminals and administers a psychopathy test. The 25 criminals produce a mean score of 54.4. In the general population, psychopathy is normally distributed with μ = 50 and σ = 10. Do habitual criminals exhibit greater psychopathy than the general population? What is the observed value of the test statistic?

2.20

If a researcher does a one-tailed test using z and sets alpha = .01, which of the following is the critical value for z?

2.33

Imagine that a class has 12 freshman, 28 sophomores, 20 juniors, and 10 seniors. If two people are selected from this group using random sampling, and the first selection is a sophomore, what is the probability that the second selection is also a sophomore?

28/70

The standard deviation of the scores in the population X = {5, 7, 11, 13} is closest to. (You should be able to do this without serious computation.)

3

The histogram at right depicts the heights (in inches) for a sample of college-age women. The standard deviation of the sample is 3". If every one of these women were 2" taller what would the standard deviation of their heights be?

3"

For the four scores: X = {1, 4, 6, 7}, what is the value of (ΣX)2 ?

324 (before adding)

Assume that a normally-distributed population has μ = 60 and σ = 25. If you took all possible samples of size n = 25 from this population, and found the mean for each sample, the standard deviation of all those means would be .

5

Assume that a normally-distributed population has μ = 60 and σ = 25. If you took all possible samples of size n = 25 from this population, and found the mean for each sample, the mean of all those means would be .

60

A statistics teacher gave an exam and the class had a mean score of 78, with an SD of 8 (this is the original scale). The teacher, bothered that the exam turned out to be so easy, decided to transform the scores to a new scale with a mean score of 70 and a standard deviation of 12. If a student got a 72 on the original scale, what would this student's score be on the new scale? (Please show any work you do.)

61

The histogram at right depicts the heights (in inches) for a sample of college-age women. The mean of the sample is 64". If every one of these women were 2" taller, what would their mean height be?

66"

For the following population of scores: 9, 9, 5, 8, 8, 9, what is the mean?

8

For the following population of scores: 9, 9, 5, 8, 8, 9, what is the median?

8.5

For the following population of scores: 9, 9, 5, 8, 8, 9, what is the mode?

9

In an analysis of variance, what is a factor?

An independent (or quasi-independent) variable

A psychologist would like Elaine the effect of sugar consumption on the activity level of children. Three samples of children are selected. One group gets no sugar, one group gets a small dose, and one group gets a large dose. The psychologist records the activity level for each child. What procedure should be used to test the null hypothesis research?

ANOVA

In a race, Amari finished in 60 seconds, while Jordan's finishing time—as a z-score—was +1.50. If the mean of all the racers was 54 seconds and the standard deviation was 6, who finished faster (that is, whose time is lower), Amari or Jordan? (If you do any computations, please show them.)

Amari

In the graphs above, part of the standard normal distribution is shaded in. Each graph has a letter below it. Which of the graphs (A, B, or C) corresponds to the two-tailed critical region when alpha = .05?

B

In hypothesis testing, why are hypotheses stated in terms of population parameters instead of sample statistics?

Because it is the population that is ultimately what the research is about.

Please answer questions 25 through 29 based on the following study description: A researcher wants to know if taking notes by hand leads to better learning than taking notes on a laptop. Students in a large science lecture course are randomly assigned to take notes by hand or on a laptop. The researcher records grades (percentage of questions correct) on a final exam to measure learning. How is the dependent variable operationalized?

By the final exam grade

In the graphs below, part of the standard normal distribution is shaded in. Each graph has a letter below it. Which of the graphs (A, B, or C) corresponds to the one-tailed p-value when zobs = 2.5?

C

In a study comparing more than two treatment conditions, why should you use analysis of variance rather than separate t-tests?

Conducting several t-tests would increase the risk of a Type I error

Consider the following two experiments. In experiments A, there are three treatments with M1=8, M2=10, & M3=12. In Experiment B, there are three treatments with M1=5, M2=10, & M3=15. Assume the samples sixes in both experiments are the same. Which experiment has a greater value for MSbetween? (You don't have enough info to compute precise answers.)

Experiment B

In an independent samples t test, assuming all other factors are held constant, if the size of the two samples is increased, the absolute value of the t statistic (that is Tobs) will _______?

Get larger (farther from zero_

In an independent-samples t-test, assuming all other factors are held constant, if the difference between the two sample means is increased, the absolute value of the t statistic (that is Tobs) will _____.

Get smaller (closer to zero)

Answer questions 14-21 based on this description of a study: A college dean wanted to answer the question of whether living off-campus (n=14) is associated with lower grades. To test this belief, the dean obtained a random sample of students living on campus (n=16) and looked up their GPAs. Among, those living on-campus, the mean GPA was 2.9 with SS = 0.6. Among those living off-campus, the mean GPA was 2.7 with SS = 0.8. Assume that the dean wants to do a hypothesis test to answer of interest. What is the dependent variable?

Grades

Answer questions 19-28 based on this description of a study: A researcher wants to determine whether habitual criminals exhibit greater psychopathy than seen in the general population. To test this, the researcher obtains a random sample of n = 25 habitual criminals and administers a psychopathy test. The 25 criminals produce a mean score of 54.4. In the general population, psychopathy is normally distributed with μ = 50 and σ = 10. Do habitual criminals exhibit greater psychopathy than the general population? What is the null hypothesis in terms of parameters/symbols?

H0: μ = 50

Answer questions 19-28 based on this description of a study: A researcher wants to determine whether habitual criminals exhibit greater psychopathy than seen in the general population. To test this, the researcher obtains a random sample of n = 25 habitual criminals and administers a psychopathy test. The 25 criminals produce a mean score of 54.4. In the general population, psychopathy is normally distributed with μ = 50 and σ = 10. Do habitual criminals exhibit greater psychopathy than the general population? What is the alternative/research hypothesis in terms of parameters/symbols?

H0: μ > 50

Answer questions 19-28 based on this description of a study: A researcher wants to determine whether habitual criminals exhibit greater psychopathy than seen in the general population. To test this, the researcher obtains a random sample of n = 25 habitual criminals and administers a psychopathy test. The 25 criminals produce a mean score of 54.4. In the general population, psychopathy is normally distributed with μ = 50 and σ = 10. Do habitual criminals exhibit greater psychopathy than the general population? Briefly describe the population being studied.

Habitual criminals

Answer questions 19-28 based on this description of a study: A researcher wants to determine whether habitual criminals exhibit greater psychopathy than seen in the general population. To test this, the researcher obtains a random sample of n = 25 habitual criminals and administers a psychopathy test. The 25 criminals produce a mean score of 54.4. In the general population, psychopathy is normally distributed with μ = 50 and σ = 10. Do habitual criminals exhibit greater psychopathy than the general population? What is the null hypothesis in words?

Habitual criminals exhibit psychopathy that is no different from the general population.

Answer questions 19-28 based on this description of a study: A researcher wants to determine whether habitual criminals exhibit greater psychopathy than seen in the general population. To test this, the researcher obtains a random sample of n = 25 habitual criminals and administers a psychopathy test. The 25 criminals produce a mean score of 54.4. In the general population, psychopathy is normally distributed with μ = 50 and σ = 10. Do habitual criminals exhibit greater psychopathy than the general population? Based on your decision, which conclusion below is the best one?

Habitual criminals have a significantly greater level of psychopathy than the general population.

A researcher conducts a study to examine how serotonin (a neurotransmitter) is related to aggression. One sample of rats serves as a control group and receives a placebo that does not affect normal serotonin levels. A second sample of rats receives a drug that lowers brain levels of serotonin. Then the researcher tests the animals by recording the number of aggressive responses each of the rats displays. What procedure should be used to test the null hypothesis in this research?

Independent-samples t-test

Compared to an independent samples design, a repeated measure study is more likely to find a significant effect because in reduces the contribution of variance due to ______.

Individual differences

Answer questions 14-21 based on this description of a study: A college dean wanted to answer the question of whether living off-campus (n=14) is associated with lower grades. To test this belief, the dean obtained a random sample of students living on campus (n=16) and looked up their GPAs. Among, those living on-campus, the mean GPA was 2.9 with SS = 0.6. Among those living off-campus, the mean GPA was 2.7 with SS = 0.8. Assume that the dean wants to do a hypothesis test to answer of interest. What is the independent or quasi-independent variable in this study?

Living situation/location

Please answer questions 25 through 29 based on the following study description: A researcher wants to know if taking notes by hand leads to better learning than taking notes on a laptop. Students in a large science lecture course are randomly assigned to take notes by hand or on a laptop. The researcher records grades (percentage of questions correct) on a final exam to measure learning. What is the independent variable?

Method of note taking

A geologist classifies the types of rocks they find as either igneous, sedimentary, or metamorphic. What scale is being used to measure agreement in this case?

Nominal

Please answer questions 25 through 29 based on the following study description: A researcher wants to know if taking notes by hand leads to better learning than taking notes on a laptop. Students in a large science lecture course are randomly assigned to take notes by hand or on a laptop. The researcher records grades (percentage of questions correct) on a final exam to measure learning. What scale is the independent variable measured on?

Nominal

Which of the following statements about one-tailed hypothesis tests is not true?

One-tailed tests involve different degrees of freedom value than a comparable two-tailed

Given the same population information as in #14 above, if n were greater than 9, what would happen to the probability you answered #14 with (would it go up, down, or stay the same)?

Probability would go up

Answer questions 19-28 based on this description of a study: A researcher wants to determine whether habitual criminals exhibit greater psychopathy than seen in the general population. To test this, the researcher obtains a random sample of n = 25 habitual criminals and administers a psychopathy test. The 25 criminals produce a mean score of 54.4. In the general population, psychopathy is normally distributed with μ = 50 and σ = 10. Do habitual criminals exhibit greater psychopathy than the general population? What is the dependent variable?

Psychopathy

Answer questions 14-21 based on this description of a study: A college dean wanted to answer the question of whether living off-campus (n=14) is associated with lower grades. To test this belief, the dean obtained a random sample of students living on campus (n=16) and looked up their GPAs. Among, those living on-campus, the mean GPA was 2.9 with SS = 0.6. Among those living off-campus, the mean GPA was 2.7 with SS = 0.8. Assume that the dean wants to do a hypothesis test to answer of interest. What is your decision about the null hypothesis?

Reject

Answer questions 19-28 based on this description of a study: A researcher wants to determine whether habitual criminals exhibit greater psychopathy than seen in the general population. To test this, the researcher obtains a random sample of n = 25 habitual criminals and administers a psychopathy test. The 25 criminals produce a mean score of 54.4. In the general population, psychopathy is normally distributed with μ = 50 and σ = 10. Do habitual criminals exhibit greater psychopathy than the general population? What is your decision about the null hypothesis?

Reject

Answer questions 19-28 based on this description of a study: A researcher wants to determine whether habitual criminals exhibit greater psychopathy than seen in the general population. To test this, the researcher obtains a random sample of n = 25 habitual criminals and administers a psychopathy test. The 25 criminals produce a mean score of 54.4. In the general population, psychopathy is normally distributed with μ = 50 and σ = 10. Do habitual criminals exhibit greater psychopathy than the general population? What is the operational definition of the dependent variable the research used?

Scores on a psychopathy test

A researcher is interested in examining whether children with ADHD watch more TV than children who are not diagnosed with ADHD. The researcher obtains a sample of children (8-12 years old) who have been diagnosed with ADHD. The average time spent watching TV for the sample is M = 3.9 hrs/day. Assume that average TV watching time for the general population of 8-12 year old children is μ = 3.1 hrs/day. What procedure should be used to test the null hypothesis in this research?

Single sample t-test

Answer questions 14-21 based on this description of a study: A college dean wanted to answer the question of whether living off-campus (n=14) is associated with lower grades. To test this belief, the dean obtained a random sample of students living on campus (n=16) and looked up their GPAs. Among, those living on-campus, the mean GPA was 2.9 with SS = 0.6. Among those living off-campus, the mean GPA was 2.7 with SS = 0.8. Assume that the dean wants to do a hypothesis test to answer of interest. Which of the following is the best version of the null hypothesis in words?

Students who live on-campus get the same grades as those who live off-campus

Imagine that a memory researcher investigates the effect of chronic alcohol abuse on memory. The researcher recruits a sample of n = 16 individuals who have abused alcohol for years and gives them a standardized memory test that is known to have μ = 50 with σ = 6 in the general population. If the researcher makes a Type I error, what conclusion did the researcher reach and what is the reality of the situation?

The researcher concluded that alcohol abuse significantly affects memory but in reality it does not have any effect.

A researcher is interested in whether children with ADHD tend to watch more TV than children who are not diagnosed with ADHD. To examine this, the researcher obtains a sample of n = 36 children who have been diagnosed with ADHD. Each child's TV-watching time is recorded. The sample has an average of M = 4.9 hours/day. Assume that the average TV- watching time in the general population of children is μ = 4.1 hours/day. Which of the following statements is most correc

The researcher should do a one-tailed test because they're interested in whether children with ADHD watch more TV than usual.

Answer questions 14-21 based on this description of a study: A college dean wanted to answer the question of whether living off-campus (n=14) is associated with lower grades. To test this belief, the dean obtained a random sample of students living on campus (n=16) and looked up their GPAs. Among, those living on-campus, the mean GPA was 2.9 with SS = 0.6. Among those living off-campus, the mean GPA was 2.7 with SS = 0.8. Assume that the dean wants to do a hypothesis test to answer of interest. Based on your decision, which conclusion below is the best ones?

Those living on campus have significantly higher grades than those living off campus

Please answer questions 25 through 29 based on the following study description: A researcher wants to know if taking notes by hand leads to better learning than taking notes on a laptop. Students in a large science lecture course are randomly assigned to take notes by hand or on a laptop. The researcher records grades (percentage of questions correct) on a final exam to measure learning. True or false: This is an experiment.

True

A leading supplier of laboratory rats has one particular strain of rats that weighs, on average, 2 pounds, with a standard deviation of 0.5. One day the company receives orders from three research universities, A, B, and C, for 10, 50, and 100 rats, respectively. If the selection of rats is random, which university is most likely to receive a shipment weighing (on average) close to 2 pounds?

University C

Under what circumstances would a score that is below the mean by 3 points appear to be very far from the mean?

When the standard deviation is much less than 3

Which of the following best describes what is meant when the results of a study lead to a hypothesis test in which the p- value is reported to be less than .05 (i.e., p < .05)?

the probability of the getting the data observed (or more extreme) was less than .05 if the null were true note: p values are about data, not hypotheses

For the past 20 years prior to 2022, the high temperature on April 15th in a particular city had a mean of 62 degrees with a standard deviation of 12. In 2022, the high temperature on April 15th was 68 degrees. Based on this information, which of the following best describes last year's temperature on April 15th?

a little above average (1/2 a standard deviation is not very far from average)

A sampling distribution of means consists of .

the sample means for all the possible random samples (of a specific size) from a population

The histogram above and to the right depicts the heights (in inches) for a sample of college-age women. Why is a histogram appropriate for these data?

because height is the continuous variable

Which of the following things can a researcher do to increase statistical power?

increase sample size (n)

Which of the following best describes the information the standard deviation, σ, provides about the relationship between the scores in a population and the mean of those scores, μ.

it's the typical distance between all of the scores and the mean

Please answer questions 25 through 29 based on the following study description: A researcher wants to know if taking notes by hand leads to better learning than taking notes on a laptop. Students in a large science lecture course are randomly assigned to take notes by hand or on a laptop. The researcher records grades (percentage of questions correct) on a final exam to measure learning. What construct is the dependent variable in this study?

learning

In a hypothesis test using z, values of Zobs that have an absolute value greater than Zcrit come from .

sample values that are very unlikely to be obtained if H0 is true

Imagine that the mean composite ACT score for the entire incoming freshman class at a university is 23. However, if you select a random sample of twenty freshman and compute their mean composite ACT score, you probably will not get exactly 23. The statistical concept that is used to explain the natural difference that exists between the mean of a sample and the mean of the population from which the sample was selected is called .

sampling error

Which of the following is the best definition of sampling error?

the discrepancy between a sample statistic and the corresponding population parameter

In a statistics class, imagine that you have three exams and that your course grade is based on the "center" of those three exams. If you have one very good exam score (in the 90s) and two average exam scores (in the high 70s), which of the following would give you the best course grade?

the mean (it incorporates the high score!)

What is the general purpose of having a measure of central tendency?

to have a single number represent a group of numbers

If you have a score of X = 75 on an exam, which set of parameters would give you the best grade relative the rest of the class? That is, if your score is 75, which of the following makes you look best?

μ=60 and σ=5

Answer questions 14-21 based on this description of a study: A college dean wanted to answer the question of whether living off-campus (n=14) is associated with lower grades. To test this belief, the dean obtained a random sample of students living on campus (n=16) and looked up their GPAs. Among, those living on-campus, the mean GPA was 2.9 with SS = 0.6. Among those living off-campus, the mean GPA was 2.7 with SS = 0.8. Assume that the dean wants to do a hypothesis test to answer of interest. Which of the following is the best version of the null hypothesis in parameters?

μon-campus = μoff-campus