STATS 2
C
A survey was conducted to get an estimate of the proportion of smokers among the graduate students. Report says 38% of them are smokers. Chatterjee doubts the result and thinks that the actual proportion is much less than this. Choose the correct choice of null and alternative hypothesis Chatterjee wants to test. a) Ho: p=.38 versus Ha: p .38. b) Ho: p=.38 versus Ha: p > .38. c) Ho: p=.38 versus Ha: p< .38. d) None of the above.
A
A two tailed test is _____ powerful than a one tailed test if we are sure the difference is in the direction that we would have predicted a) more b) less c) equally d) we cannot tell
B
A two-tailed hypothesis test is being used to evaluate a treatment effect with α = .05. If the sample data produce a z-score of z = −2.24, what is the correct decision? a. Reject the null hypothesis and conclude that the treatment has no effect b. Reject the null hypothesis and conclude that the treatment has an effect c. Fail to reject the null hypothesis and conclude that the treatment has no effect d. Fail to reject the null hypothesis and conclude that the treatment has an effect
B
After running a test on the mean number of jelly beans that men and women ate over the course of the year, I conclude that men eat significantly more jelly beans than women. If men and women actually eat the same number of jelly beans, my conclusion is a) a valid conclusion b) a Type I error c) a Type II error d) an example of power
B
Assuming that other factors are held constant, which of the following would tend to increase the likelihood of rejecting the null hypothesis? a. Decrease the sample size b. Increase the sample mean difference c. Increase the sample variance d. None of the other 3 options would increase the likelihood.
POWERFUL
BIGGER THE SAMPLE SIZE THE MORE ______ YOUR STUDY IS
B
By convention, we often reject the null hypothesis if the probability of our result, given that the null hypothesis were true, is a) greater than .95 b) less than .05 c) greater than .05 d) either b or c
B
Determining which statistical test to use in an analysis of data is based upon which two factors? A. The sample size and the purpose of the statistical inference B. The type of data and the purpose of the statistical inference. C. The sample size and the type of data. D. None of these choices.
A one-tailed test is associated with a ________________ hypothesis
Directional
D
Failing to reject the null hypothesis when the research hypothesis is true is _____. a) Effect size b) Power c) Type I error d) Type II error
B
For a given sample size n, if the level of significance is decreased, the power of the test will: A. increase. B. decrease. C. remain the same. D. Not enough information to tell
C
For a hypothesis test evaluating the effect of a treatment on a population mean, what basic assumption is made concerning the treatment effect? a. If there is a treatment effect, it will increase the scores. b. If there is a treatment effect, it will decrease the scores. c. If there is a treatment effect, it will add (or subtract) a constant to each score. d. If there is a treatment effect, it will multiply (or divide) each score by a constant.
B
For a test with the null hypothesis Ho: p = 0.5 vs. the alternative Ha: p > 0.5, the null hypothesis was not rejected at level alpha=.05. Das wants to perform the same test at level alpha=.025. What will be his conclusion? a) Reject H0. b) Fail to Reject H0. c) No conclusion can be made. d) Reject Ha.
lower
High Alpha level = ____ power
B
How does a large Cohen's d influence power? a) Decreases power b) Increases power c) Cohen's d has little influence on power d) It can increase or decrease power
D
If I do a study, and I get a result of p = .42, what should I conclude? o A. I should reject the null hypothesis o B. I should accept the null hypothesis o C. I should fail to reject the null hypothesis o D.B and C
A
If a psychologist tests whether a new teaching method is more effective than the old method, the research hypothesis is that... o a. the new method is more effective than the old method o b. the old method is more effective than the new method o c. there is no difference in effectiveness between the two methods o d. there is a difference in effectiveness between the two methods, but no prediction has been made
Reject null hypothesis
If the cutoff Z score on the comparison distribution is +/- 1.96 and the sample Z score on the comparison distribution is -2.05, the correct decision is to _______ the null hypothesis.
D
If we reject the null hypothesis when it is false, then we have committed: A. a Type II error. B. a Type I error. C. both a Type I error and a Type II error. D. neither a Type I error nor a Type II error
A
If we reject the null hypothesis, we conclude that: A. there is enough statistical evidence to infer that the alternative hypothesis is true. B. there is not enough statistical evidence to infer that the alternative hypothesis is true. C. there is enough statistical evidence to infer that the null hypothesis is true. D. there is not enough statistical evidence to infer that the null hypothesis is true.
B
If you get a significant result in your study, and you fail to reject the null, you are either making a: A. Correct rejection or false negative o B. Hit or false negative o C. Correct rejection or false positive o D. Hit or false positive
C
If you get a significant result in your study, and you reject the null, you are either making a: o A. Correct rejection or false negative o B. Hit or false negative o C. Correct rejection or false positive o D. Hit or false positive
Type I error
If you rejected a true null hypothesis, you most likely committed a(n)
B
If you rejected a true null hypothesis, you most likely committed a(n): a) Faux pas b) Type I error c) An underestimation of power error d) Type II error
B
If you set an extreme alpha level (say .001), what is the effect on the probability of a Type II error? a) The probability is low b) The probability is high c) The probability is ~80% d) Alpha level does not affect decision errors
C
In a two-tail test for the population proportion, if the null hypothesis is rejected when the alternative hypothesis is true: A. a Type I error is committed. B. a Type II error is committed. C. a correct decision is made.
A
In order to determine the p-value, which of the following is not needed? A. The level of significance. B. Whether the test is one-tail or two-tail. C. The value of the test statistic. D. All of these choices are true.
1. Large effect size 2. Small SD 3. Large sample size
List 3 ways you can obtain MORE statistical power.
Effect size
Meta analyses are useful for figuring out average ____________ across studies.
A two-tailed test is associated with a ________________ hypothesis
Non-directional
CUTOFF SAMPLE SCORE
Point in hypothesis testing, on the comparison distribution at which, if reached or exceeded by the sample score, you reject the null hypothesis
C
A null hypothesis was rejected at level alpha=0.10.What will be the result of the test at level alpha=0.05? a) Reject Ho b) Fail to Reject Ho c) No conclusion can be made d) Reject Ha
Research hypothesis
A prediction like this about the difference between populations is called
Large
A psychologist conducts a study and finds that d = 1.41. This effect size would most likely be described as:
Small OR Small to Medium
A psychologist finds an effect size of d = .23. Based on conventions in psychology, this effect size would be described as _________.
D
A quantitative measure of the difference between two groups is called (i.e. the strength of the phenomenon) ... a. Significance b. Probability c. Power d. Effect size
B
A researcher administers a treatment to a sample of participants selected from a population with µ = 80. If the researcher obtains a sample mean of M = 88, which combination of factors is most likely to result in rejecting the null hypothesis? a. σ = 5 and α = .01 b. σ = 5 and α = .05 c. σ = 10 and α = .01 d. σ = 10 and α = .05
C
A researcher conducts a hypothesis test using a sample from an unknown population. If the t statistic has df = 30, how many individuals were in the sample? a. n = 29 b. n = 30 c. n = 31 d. Cannot be determined from the information given
A
A researcher evaluates a treatment effect using a two-tailed hypothesis test with α = .05, and the decision is to reject the null hypothesis. If the researcher switched to a one-tailed test using the same sample, what decision would be made? a. Definitely reject the null hypothesis with α = .05 and maybe reject with α = .01 b. Definitely reject the null hypothesis with α = .05 and with α = .01 c. Definitely fail to reject the null hypothesis with either α = .05 or with α = .01 d. It is impossible to predict the outcome of the one-tailed test.
D
A researcher selects a sample and administers a treatment to the individuals in the sample. If the sample is used for a hypothesis test, what does the null hypothesis (H0) say about the treatment? a. The treatment causes a change in the scores. b. The treatment adds a constant to each score. c. The treatment multiplies each score by a constant. d. The treatment has no effect on the scores.
Females fall asleep more than males & males and females fall asleep at the same rate
A researcher was interested in seeing if males fall asleep more than females in large lecture classes during in-class videos. The null hypothesis of this study is ________.
B
Risk of a type I error is closely but inversely related to a) statistical power b) alpha level c) sample standard deviation d) population size
A
Risk of a type II error is closely but inversely related to a) statistical power b) alpha level c) sample standard deviation d) population size
C
Sampling distributions help us test hypotheses about means by a) telling us exactly what the population mean is b) telling us how variable the population is c) telling us what kinds of means to expect if the null hypothesis is true d) telling us what kinds of means to expect if the null hypothesis is false
1. Its mean 2. Its spread (which you measure using the variance and standard deviation) 3. Its shape
The 3 key characteristics of the comparison distribution that you need to determine are:
C
The basic idea behind hypothesis testing a) depends on the kind of test you want to run b) has little to do with whatever data you collect c) is largely the same across a wide variety of procedures d) is important only if you want to compare two populations
B
The fluctuation in the value of a statistical index such as the mean from one sample to the next is called a) parameter uncertainty b) sampling error c) conditional probability d) interval estimation
A
The hypothesis of most interest to the researcher is: A. the alternative hypothesis (research hypothesis) B. the null hypothesis. C. both hypotheses are of equal interest. D. Neither hypothesis is of interest.
D
The level of significance can be: A. any number between -1.0 and 1.0. B. any number greater than zero. C. any number greater than 1.96 or less than -1.96. D. None of the above.
Alpha level
Type I error is associated with the
D
We can anticipate the likelihood of various possible values of sample statistics based on the a) alternative hypothesis b) standard deviation c) grouped frequency distribution d) the sampling distribution
NOTHING because it does not exist
What is the a p value of -.5
Standard error of the mean (SEM) or the standard error (SE).
What term is used to identify the standard deviation of the distribution of means? Tells you: On average, this is how much scores deviate from the mean of the distribution of means
B
What term is used to identify the standard deviation of the distribution of means? a. the expected value of the mean b. the standard error of the mean c. the sample mean d. the central limit mean
E
When are p-values negative? a) when the test statistic is negative. b) when the sample statistic is smaller than the proposed value of the parameter c) when the confidence interval includes only negative values d) when we fail to reject the null hypothesis e) never
Critical value
cutoff sample score is also called the
Effect size
measure of the difference between population means.
Directional hypothesis
predicting a particular direction of differences between populations
Hypothesis testing
procedure for deciding whether the outcome of a study (results from a sample) supports a particular theory or practical innovation (which is thought to apply to a population)
Type 1
rejection of a true null hypothesis (also known as a "false positive" finding)
less
researchers reject the null hypothesis if the probability of getting a sample score this extreme (if the null hypothesis were true) is _____ than 5%. This probability is usually written as p < .05.
Research (alternative)
there is a difference in our populations
Null
there is no difference between our populations
C
A Type II error is committed if we make: A. a correct decision when the null hypothesis is false. B. a correct decision when the null hypothesis is true. C. an incorrect decision when the null hypothesis is false. D. an incorrect decision when the null hypothesis is true
small
.20 is considered
medium
.50 is considered
large
.80 is considered
B
A health psychologist is interested in the effectiveness of a new type exercise on reducing the rate of heart attacks because this new exercise requires no equipment and, therefore, can be done without cost. What is the comparison distribution? o a. the distribution of people who participate in the new exercise program o b. the distribution of people who do not participate in the new exercise program o c. the distribution of people who have heart attacks o d. the distribution of people who do not have heart attacks
p value
=probability
E
A HYPOTHESIS IS NOT A(N): A. Question B. Random guess C. Observation D.Experiment E. All the above
D
A Type I error is committed if we make: A. a correct decision when the null hypothesis is false. B. a correct decision when the null hypothesis is true. C. an incorrect decision when the null hypothesis is false. D. an incorrect decision when the null hypothesis is true.
D
The mean of a distribution of means is the same as.... a. standard error b. variance of the population of individuals c. sample mean d. mean of the population of individuals
E
The null hypothesis Ho: p=.5 against the alternative Ha: p>.5 was rejected at level alpha=0.01. Nate wants to know what the test will result at level alpha=0.10. What will be his conclusion? e) Reject H0. f) Fail to Reject H0. g) No conclusion can be made. h) Reject Ha.
A
The null hypothesis represents the statement that a) a population means are equal b) population means differ between groups c) it is the hypothesis you generally hope to prove d) exciting things are going to happen
B
The p-value criterion for hypothesis testing is to reject the null hypothesis if: A. p-value = a B. p-value < a C. p-value > a D. - a < p-value < a
A
The p-value is a probability that measures the support (or lack of support) for the A. Null Hypothesis B. Alternate Hypothesis C. Null or Alternate Hypothesis D. The sample proportion
D
The power of a test is denoted by: A. a B. B C.1- a D.1- B
C
The power of a test is measured by its capability of: A. rejecting a null hypothesis that is true. B. not rejecting a null hypothesis that is true. C. rejecting a null hypothesis that is false. D. not rejecting a null hypothesis that is false
c
The probability of a Type I error is denoted by: A. B B. 1- B C. a D. 1- a
A
The probability of a Type I1 error is denoted by: A. B B. 1- B C. a D. 1- a
C
The rejection rejoin corresponds with sample outcomes which would lead us to reject a) the sample as biased b) the data's validity c) the null hypothesis d) the notion of 'significance'
(a) each sample is of 30 or more individuals or (b) the distribution of the population of individuals is normal
The shape of a distribution of means is approximately normal if either
A
The standard deviation of a sampling distribution is known as a) the standard error b) the variance c) error d) the sampling deviation
the standard error of the mean (SEM) or the standard error (SE
The standard deviation of the distribution of means is also called
C
To increase the value of estimated Cohen's d, a researcher increases the sample size. Will this change the value of d? a) Yes; as sample size increases, effect size increases. b) No; as sample size increases, effect size decreases. c) No; the sample size is not used to compute effect size.
A
To obtain a sampling distribution of the mean we would a) calculate a mean and compare it to the standard deviation b) calculate a mean and compare it to the standard error c) calculate many means and plot them d) look the sampling distribution up in a book
Reject null accept alternative
Trying to prove the null hypothesis false ?
principle of falsifiability
When using a hypothesis testing framework, we are subject to the
B
Which of the following is an accurate definition of a Type I error? a. Rejecting a false null hypothesis b. Rejecting a true null hypothesis c. Failing to reject a false null hypothesis d. Failing to reject a true null hypothesis
B
Which of the following is an appropriate null hypothesis? A. The proportion of a population is equal to 60. B. The proportion of a sample is equal to 60. C. The proportion of a population is not equal to 60. D. All of these choices are true.
B
Which of the following is directly addressed by the null hypothesis? a. The population before treatment b. The population after treatment c. The sample before treatment d. The sample after treatment
B
Which of the following statements is not true? A. The probability of making a Type II error increases as the probability of making a Type I error decreases. B. The probability of making a Type II error and the level of significance are the same. C. The power of the test decreases as the level of significance decreases. D. All of these choices are true.
C
Which of the following would be an appropriate alternative hypothesis? A. The proportion of a population is equal to 70. B. The proportion of a sample is equal to 70. C. The proportion of a population is greater than 70. D. The proportion of a sample is greater than 70
B
You complete a hypothesis test using α = .05, and based on the evidence from the sample, your decision is to fail to reject the null hypothesis. If the treatment actually does have an effect, which of the following is true? a. You have made a Type I error. b. You have made a Type II error. c. You might have made a Type I error, but the probability is only 5% at most. d. You have made the correct decision.
Hypothesis
a prediction intended to be tested in a research study Example: Chocolate ice cream is better than vanilla ice cream.
Distribution of means
distribution of means of samples of a given size from a population (also know as the sampling distribution of the mean)
Theory
set of principles that attempt to explain an important psychological process Example: Chocolate ice cream distracts us from the burdens of self-hood and helps us be happier (at least while eating said ice cream) so it is objectively better than all other types of ice cream
samples; population
the data from _____ resembles the data we would get from the _______
Comparison distribution
the distribution that represents the population situation if the null hypothesis is true!
Type 2
the failure to reject a false null hypothesis (also known as a "false negative" finding)
