Research Methods Final
*The larger the sample size, a. the smaller the standard error and the narrower the confidence interval. b. the smaller the standard error and the wider the confidence interval. c. the larger the standard error and the narrower the confidence interval. d. he larger the standard error and the wider the confidence interval
a
* Having committed yourself to a one-tailed test, the formal statement of the null hypothesis should be expanded to include values of the population mean a. in either direction. b. in the direction of no concern. c. suggested by the observed sample mean. d. more deviant that the critical z.
b
*Dr. Fletcher is interested in whether joining a fraternity/sorority causes people to become more concerned about their attractiveness and appearance. He recruits a group of 55 freshmen (25 males, 30 females) who are planning to go through fraternity/sorority recruitment on his campus. After they join, he gives them a measure of attractiveness concern/appearance concern (the Body Concern Scale). In addition to measuring the group of participants who joined a fraternity/sorority, Dr. Fletcher decides to give the same measure to another group of 55 participants who decided to not join a fraternity/sorority. After conducting the study, Dr. Fletcher finds out that the people who joined a fraternity/sorority all saw a documentary on body image sponsored by the InterGreek Council the night before recruitment began. This threat to internal validity is known as a: a. Selection threat b. Selection-history threat c. History threat d. Testing threat
b
If the probability of some outcome is small, that outcome is viewed as a. common. b. rare. c. real. d. impossible.
b
*Cohen's d for two independent samples is obtained by dividing the observed mean difference by a. the estimated standard error. b. the square root of the pooled variance. c. the best estimate of the sample standard deviation. d. none of the above.
d
*Interaction occurs whenever the effects of one factor are a. not consistent. b. consistent. c. consistent for all values of the second factor. d. not consistent for all values of the second factor.
d
A researcher reports t(22) = 5.30, p < .01 for an independent-measures experiment. How many individuals participated in the entire experiment? a. 20 b. 21 c. 23 d. 24
d
Dr. Bloedorn is a health psychologist who researches nutrition. She is curious as to whether a new drink additive will help people consume fewer calories during a meal. The drink additive is a white, odorless, tasteless powder that a person can add to any drink. She collects a random sample of 63 overweight students on campus and measures the calories they eat during lunch, using a calorimeter. She then gives this additive to the same 63 participants to use at dinner and measures how many calories they eat (again, using the calorimeter). The addition of a group that does not use the drink additive but adds a similar-looking substance that they think is the additive would help Dr. Bloedorn address which of the following threats to internal validity? a. History b. Observer bias c. Instrumentation d. Placebo effects
d
If an investigator reports that main effects exist for both factors, this implies a. that an interaction could not possibly be present. b. that an interaction probably is present. c. that an interaction probably isn't present. d. nothing whatsoever about the interaction.
d
the standard normal curve a. appears in infinitely many forms b. has a mean of 100 and a standard deviation of 7. c. is unrelated to any other normal curve. d. is the single normal curve for which tables are available.
d
to evaluate how well a study supports a frequency claim, you need to focus on evaluating which of the following validities? a. construct validity and external validity b. statistical validity and external validity c. internal validity and external validity d. internal validity and construct validity e. construct validity, external validity, and statistical validity
e
true or false: the central limit theorem ensures that the shape of the sampling distribution of the mean equals the shape of the population
false
true or false: the central limit theorem states that, regardless of sample size, the shape of the sampling distribution of the mean is normal
false
true or false: the central limit theorem states that, with sufficiently larger sample sizes, the shape of the population is normal
flase
at a critical z value of 1.96, do you reject or retain the null at z = -2.00
reject, 2.00 is more negative
at a critical z value of 1.96, do you reject or retain the null at z = 2.00
reject, 2.00 is more positive
at a critical z value of 1.96, do you reject or retain the null at z=1.70
retain, 1.70 is less positive
true or false: the central limit theorem applies to the shape of the sampling distribution -- not to the shape of the population and not to the shape of the sample
true
true or false: the mean of all sample means equals 100, if in fact, the population mean equals 100
true
true or false: the mean of all sample means is interchangeable with the population mean
true
true or false: the standard error of the mean roughly measures the average amount by which sample means deviate from the population mean
true
Before the null hypothesis can be rejected at a given level of significance, observed values of the t ratio (compared to those for the z ratio) a. must deviate further from zero. b. needn't deviate as far from zero. c. must deviate the same distance from zero. d. must deviate from zero.
a
For an experiment involving 3 levels of factor A and 3 levels of factor B, with a sample of n = 8 in each treatment condition, what are the df values for the F-ratio for the AxB interaction? a. 4, 63 b. 8, 63 c. 2, 63 d. 6, 63
a
In twofactor ANOVA, an F ratio is calculated for each different a. sum of squares. b. mean square. c. null hypothesis. d. factor.
c
A pollster reports, with 95 percent confidence, that between 55 and 61 percent of all Americans favor mandatory drug testings for employees in positions of public trust (bus drivers, airline pilots, etc). The boundaries of this confidence interval (55 to 61 percent) suggest that a. a majority of Americans probably favor mandatory drug testing. b. a majority of Americans definitely favor mandatory drug testing. c. it is impossible to know whether a majority of Americans favor mandatory drug testing. d. all of the above are true, depending on your perspective
a
Compared to the standard error for two independent samples, that for two related samples will tend to be a. smaller. b. the same. c. approximately the same. d. large.
a
Dr. Gavin is conducting a 2 x 4 independent-groups factorial design. How many independent variables are in his study? a. 2 b. 4 c. 6 d. 8
a
For an ANOVA comparing three treatment conditions, what is stated by the null hypothesis (H0)? a. There are no differences between any of the population means. b. At least one of the three population means is different from another mean. c. All three of the population means are different from each other. d. None of the other choices is correct.
a
In an experiment involving four different groups, each consisting of 8 subjects, the critical F occupies the cell intersected by column and row degrees of freedom, respectively, of a. 3 and 28. b. 3 and 32. c. 4 and 16. d. 4 and 32.
a
The variance can be described as the a. the square of the standard deviation. b. square of the mean deviation. c. mean deviation. d. deviation of the mean.
a
*Given critical z values of ±1.96 and an observed z value of -2.40, the appropriate decision is to a. retain the null hypothesis. b. reject the null hypothesis. c. neither retain nor reject, but increase the size of the sample. d. neither retain nor reject, but conduct another investigation.
b
*Which of the following is an accurate definition of effect size? a. a measure of the absolute magnitude of the observed effect/difference, independent of sample size b. a measure of the absolute magnitude of the observed effect/difference, independent of the sample size and standard error of the mean c. a measure of the absolute magnitude of the observed effect/difference, for a particular sample size d. a measure of the absolute magnitude of the observed effect/difference, for a particular standard error of the mean
b
A class consists of 10 males and 30 females. If one student is randomly selected from the class, what is the probability of selecting a male? a. 10/30 b. 10/40 c. 1/10 d. 1/40
b
An important implication of the formula for the standard error is that whenever the sample size equals two or more, the variability of the sampling distribution is______________ the variability of the population. a. equal to b. less than c. more than d. approximately the same as
b
Even when the normality assumption is violated, the t test retains much of its accuracy as long as the a. population standard deviation is known. b. sample size isn't too small. c. observed value of t isn't too large. d. sample standard deviation isn't too small.
b
The .05 level of significance indicates a degree of rarity of one time in a. five or less. b. ten or less. c. twenty or less. d. one hundred or less.
c
The null hypothesis a. is tested indirectly. b. makes a claim about a range of values. c. usually asserts that nothing special is happening in the sample with respect to some population characteristic. d. usually is identified with the research hypothesis.
c
The t test for two independent samples has degrees of freedom equal to the a. two sample sizes combined. b. two sample sizes combined minus one. c. two sample sizes combined minus two. d. two sample sizes combined minus three.
c
To be a history threat, the external event must occur: a. Constantly during the experiment b. At the beginning of the experiment c. Systematically, affecting most members of the group d. Intentionally, affecting most members of the group
c
In the analysis of variance, the F test is equivalent to a a. directional test because only the upper tail is critical. b. directional test because all variations are squared. c. nondirectional test because only the upper tail is critical. d. nondirectional test because all variations are squared.
d
In the population distribution of 200 residents of a small town, 25 have no pets, 50 have 1 pet, 100 have 2 pets, and 25 have 3 pets. If you randomly pick a person to visit in the town, what is the probability that that resident has at least one pet? a. 25/200 b. 50/200 c. 150/200 d. 175/200
d
Which of the following is a difference between true experiments and quasi-experiments? a. Quasi-experiments cannot have comparison groups. b. Quasi-experiments cannot have pretest measures. c. Quasi-experiments do not involve different groups. d. Quasi-experiments do not use random assignment.
d
true or false: the mean of all sample means always equals the value of a particular sample mean
false
true or false: the mean of all sample means usually equals the value of a particular sample means
false
true or false: the standard error of the mean increases in value with larger sample sizes
false
true or false: the standard error of the mean measures variability in a particular sample
false
* A sample is random if the selection process generates a set of observations that is a. haphazard. b. nonsystematic. c. representative. d. none of the above
B
An investigator conducts an experiment to assess people's helping behavior when another unknown person (who is a confederate in the experiment) appears to be in trouble. The investigator manipulates two variables. One independent variable is number of bystanders (number of people present other than the participant), with levels 0, 2, and 4. The second independent variable is degree of distress that the unknown person appears to be in, with levels mild (the unknown person has a coughing fit) and severe (the unknown person has a seizure, falling down and twitching in their limbs). The investigator conducts the experiment as a within-subjects design. Which statistical procedure should be used to analyze the results? a. 2-factor within subjects ANOVA b. 1-factor between subjects ANOVA c. 2-sample repeated measures t test d. 2-factor between subjects ANOVA
a
Observer bias can threaten which of the following big validities? a. Internal validity and construct validity b. External validity and construct validity c. Internal validity and external validity d. Internal validity only
a
Sampling error can be defined as the natural discrepancy between: a. a sample statistic and its corresponding population parameter b. a sample parameter and its corresponding population statistic c. the highest and lowest values in a population distribution d. the highest and lowest values in a sample data set
a
When is there a risk of a Type I error? a. Whenever H0 is rejected b. Whenever H1 is rejected c. Whenever the decision is fail to reject H0 d. The risk of a Type I error is independent of the decision from a hypothesis test.
a
Which of the following accurately describes the critical region? a. Outcomes with a very low probability if the null hypothesis is true b. Outcomes with a high probability if the null hypothesis is true c. Outcomes with a very low probability whether or not the null hypothesis is true d. Outcomes with a high probability whether or not the null hypothesis is true
a
You need be concerned about the normality assumption for the t test for two related samples only when sample a. size is ten or less. b. size is greater than ten. c. variances are radically different. d. sizes are different.
a
In a study on the ability to recognize objects when they are rotated, participants learn the names of four objects. They are then asked to name the same four objects when rotated 36 degrees, 72 degrees, and 108 degrees. The objects also appear at three different sizes: larger, smaller, or the same size. The participants' naming accuracy is measured. What is the dependent variable? a. amount of time needed to learn the four objects b. naming accuracy c. degrees of rotation d. size of the object
b
On the basis of a random sample of 25 students from a large university, an educator estimates, with 95 percent confidence, that between 17 to 20 hours describes the mean weekly study time of all students at the university. Accordingly, we can be reasonably certain that a. 95 percent of all students study between 17 and 20 hours. b. on average, all students study between 17 and 20 hours. c. the sample mean (for the 25 students) was between 17 and 20 hours. d. all of the above
b
Regression is especially problematic in which of the following situations? a. When the experimental and comparison groups are equal at posttest b. When one group has an extremely high score at pretest c. When the experimental and comparison groups are equal at pretest d. When one group has an extremely low score at posttest
b
Which of the following accurately describes the effect of increasing the sample size? a. Increases the standard error and has no effect on the risk of a Type I error b. Decreases the standard error and has no effect on the risk of a Type I error c. Increases the risk of a Type I error and has no effect on the standard error d. Decreases the risk of a Type I error and has no effect on the standard error
b
Which of the following is a frequency claim? a. Owning a dog is related to higher life satisfaction. b. A majority of Americans like dogs. c. Debt stress associated with cardiac risk d. Being visited by dogs in the hospital causes decreases in recovery time.
b
*A sample of n = 9 scores is obtained from a population with a mean of 70 and a standard deviation of 18. If the sample mean is 76, what is the z-score for the sample mean? a. z = 0.33 b. z = 0.50 c. z = 1.00 d. z = 3.00
c
*In a two-factor design, with three values (or levels) for each factor and with five subjects in each of the resulting nine groups, the within group component has degrees of freedom equal to a. 9 b. 45 c. 36 d. 4
c
*in repeated-measures ANOVA, the error sum of squares equals the within sum of squares a. and the subject sums of squares. b. and the between group sums of squares. c. minus the subject sum of squares. d. minus the between group sum of squares.
c
A random sample of n = 60 scores is selected from a population. Which of the following distributions definitely will be normal? a. The scores in the sample will form a normal distribution. b. The scores in the population will form a normal distribution. c. The distribution of sample means will form a normal distribution. d. The sample, the population, and the distribution of sample means definitely will not be normal.
c
All of the following are true about factorial designs except a. they have at least two independent variables b. the independent variables can be either between-subjects or within-subjects c. they are best analyzed with a 1-factor ANOVA d. if both main effects and interactions occur, interactions are more important
c
Anton and his friends are discussing a study he read about in his developmental psychology class. In the study, the researcher made the claim that a majority of middle school students who are bullied have low self-esteem. Why should Anton NOT interrogate the internal validity of the study? a. Because he is a student, not a researcher b. Because the author of the study already did c. Because the claim is an association claim d. Because he has not taken statistics yet
c
Any sum of squares term always equals the a. square of the sum of all scores. b. square of the deviations of all scores about their mean. c. sum of the squared deviations of all scores about their mean. d. sum of the deviations of squared scores about their mean.
c
Dr. Fletcher is interested in whether joining a fraternity/sorority causes people to become more concerned about their attractiveness and appearance. He recruits a group of 55 freshmen (25 males, 30 females) who are planning to go through fraternity/sorority recruitment on his campus. After they join, he gives them a measure of attractiveness concern/appearance concern (the Body Concern Scale). In addition to measuring the group of participants who joined a fraternity/sorority, Dr. Fletcher decides to give the same measure to another group of 55 participants who decided to not join a fraternity/sorority. This type of design is known as a/an: a. Reversal design b. Nonequivalent groups interrupted time-series design c. Nonequivalent control group design d. Interrupted time-series design
c
Dr. Gavin decides that instead of conducting a 2 x 4 independent-groups factorial design, he is going to conduct a 2 x 4 within-subjects factorial design. Which of the following things will change? a. The number of main effects that need to be examined b. The number of interactions that need to be examined c. The number of participants needed d. The number of cells
c
Dr. Gavin is conducting a 2 x 4 independent-groups factorial design. Assuming he wants 25 people in each cell, how many participants does Dr. Gavin need to recruit? a. 100 b. 150 c. 200 d. 250
c
Greek letters are used to describe characteristics of a. samples and populations. b. samples and sampling distributions. c. sampling distributions and populations. d. samples, sampling distributions, and populations.
c
One very prevalent decision rule specifies that the null hypothesis should be rejected if the z calculated from the observation a. equals or is more positive that +1.96. b. equals or is more negative than -1.96. c. equals or is more positive than +1.96 or equals or is more negative than -1.96. d. falls between +1.96 and -1.96.
c
Scores of healthy adults on a neurological test form a normal distribution with mean = 100 and SD = 15. What conclusion can be inferred about an individual score that corresponds to a z value of -2.5? a. it falls in the general region of the population distribution b. it falls in the critical region of the distribution c. it is likely to come from the healthy distribution d. it is unlikely to come from the healthy distribution
c
Which of the following is a difference between a 2 factor between subjects ANOVA and a 2 factor within subjects ANOVA? a. The presence of an interaction term in the analysis b. The use of mean squares c. The error term used for tests d. The presence of two main effects terms in the analysis
c
Which of the following is true of instrumentation threats? a. They are the same as testing threats. b. They occur only when using mechanical instruments (e.g., blood pressure cuffs, scales). c. They can be avoided with counterbalancing. d. They are only problematic in observational research.
c
Which of the following will increase the power of a statistical test? a. Change the significance level from .05 to .01 b. Change from a one-tailed test to a two-tailed test c. Change the sample size from n = 25 to n = 100 d. None of the other options will increase power.
c