Study Guide
PSY 211 – Exam #4
Mike Hoerger
You may keep this paper copy of the exam when you have finished. You may use a simple calculator during the exam.
The exam is 120 points (3 points per question).
|1 |A “carryover effect” is potential criticism of the within-subject design. |T F |
|2 |The shape of the t-distribution becomes flatter as sample size increases. |T F |
|3 |An alpha level of .10 is typically used in statistical analyses in psychology. |T F |
|4 |Stephen Colbert using Airborne (a useless health pill) was an example of a Type II error. |T F |
|5 |It is possible for Cohen’s d to be “large” and have a result that is not statistically significant. |T F |
|6 |When conducting a between-group t-test, the p-value describes the probability that the observed mean difference is |T F |
| |merely due to chance. | |
|7 |To determine the critical value for a z-test, one must know the degrees of freedom (df) for the sample. |T F |
|8 |In twin studies, the between-group t-test is typically used to compare pairs of twins. |T F |
|9 |When writing an alternative hypothesis, a researcher is describing differences that are expected to occur at the |T F |
| |population level, rather than merely within the sample. | |
|10 |If a correlation has a p-value of 0.40, the correlation is said to be “statistically significant”. |T F |
|11 |In a study comparing a medication to a placebo, the alternative hypothesis would be that there are no differences in |T F |
| |results between the two groups. | |
|12 |When a treatment is more beneficial than expected, it is said to be “iatrogenic”. |T F |
|13 |A Type I error occurs when the researcher incorrectly accepts the alternative hypothesis. |T F |
|14 |The critical value for a one-tailed hypothesis test is less extreme than for a two-tailed hypothesis. |T F |
|15 |For a between-group t-test, Cohen’s d indicates how many standard deviations apart the two sample means are. |T F |
|16 |When conducting a z-test, the critical z-value will vary depending on the sample size used in the study. |T F |
|17 |“Sampling error” means that results can be expected to differ slightly across different groups or samples. |T F |
|18 |When conducting a t-test, choosing a stricter alpha will lead to a critical t-value that is more extreme. |T F |
|19 |The between-group t-test has greater power than the within-subject t-test. |T F |
|20 |“HA” and “H0” are both symbols for the alternative hypothesis. |T F |
|21 |How many of the following analyses allow someone to compare a sample of treated patients to a larger untreated population? |
| |between-group t-test |
| |z-test |
| |single-sample t-test |
| |repeated-measures t-test |
|a) |1 |
|b) |2 |
|c) |3 |
|22 |When writing up results in APA style, it is optional to report a negative sign for this statistic. |
|a) |r |
|b) |z |
|c) |d |
|23 |Cohen’s d is similar to r in the same way that _______ are similar to _______. |
|a) |t-tests; z-tests |
|b) |experiments; surveys |
|c) |Type II errors; Type I errors |
|24 |If Cohen’s d = .47, the effect size is… |
|a) |small |
|b) |medium |
|c) |large |
|25 |A researcher wants to examine whether a brief commercial will influence participants attitudes toward global warming. The |
| |researcher has participants rate their “belief in global warming” on a 9-point scale before and after the commercial. What type|
| |of statistical test would be used to compare participants’ scores before and after the commercial? |
|a) |single-sample t-test |
|b) |within-subject t-test |
|c) |between-group t-test |
|26 |This statistic is an example of an effect size… |
|a) |p |
|b) |r |
|c) |t |
|27 |If r2 = .13, the effect size is… |
|a) |small |
|b) |medium |
|c) |large |
|28 |This type of statistical test could be used to examine gender differences in agreeableness. |
|a) |single-sample t-test |
|b) |within-subject t-test |
|c) |between-group t-test |
|29 |A researcher finds that violent television increases aggression, d = 0.12, t = 6.48, p = .001. What can we conclude about this |
| |particular study? |
|a) |Due to a large sample, a small effect was statistically significant. |
|b) |The result is not trustworthy; it may be due to chance. |
|c) |Several outliers (atypical scores) were likely present in the data file. |
|30 |Below is a correlation table. Note that the asterisks (*) marking significant correlations have been removed. How many |
| |significant correlations does Tanning have with the other variables? |
| |Correlations |
| | |
| | |
| | |
| |89. Leader |
| |ship |
| |44. Tanning |
| |68. Physical Pain |
| |84. Body Satisfac |
| |tion |
| |91. ADHD Symp |
| |toms |
| | |
| |89. Leadership |
| |Pearson Correlation |
| |1.000 |
| |.075 |
| |.045 |
| |.167 |
| |.010 |
| | |
| | |
| |Sig. (2-tailed) |
| | |
| |.019 |
| |.161 |
| |.000 |
| |.751 |
| | |
| | |
| |N |
| |975.000 |
| |975 |
| |975 |
| |975 |
| |975 |
| | |
| |44. Tanning |
| |Pearson Correlation |
| |.075 |
| |1.000 |
| |.040 |
| |.069 |
| |.050 |
| | |
| | |
| |Sig. (2-tailed) |
| |.019 |
| | |
| |.211 |
| |.032 |
| |.122 |
| | |
| | |
| |N |
| |975 |
| |975.000 |
| |975 |
| |975 |
| |975 |
| | |
| |68. Physical Pain |
| |Pearson Correlation |
| |.045 |
| |.040 |
| |1.000 |
| |-.059 |
| |.148 |
| | |
| | |
| |Sig. (2-tailed) |
| |.161 |
| |.211 |
| | |
| |.066 |
| |.000 |
| | |
| | |
| |N |
| |975 |
| |975 |
| |975.000 |
| |975 |
| |975 |
| | |
| |84. Body Satisfaction |
| |Pearson Correlation |
| |.167 |
| |.069 |
| |-.059 |
| |1.000 |
| |-.143 |
| | |
| | |
| |Sig. (2-tailed) |
| |.000 |
| |.032 |
| |.066 |
| | |
| |.000 |
| | |
| | |
| |N |
| |975 |
| |975 |
| |975 |
| |975.000 |
| |975 |
| | |
| |91. ADHD Symptoms |
| |Pearson Correlation |
| |.010 |
| |.051 |
| |.148 |
| |-.143 |
| |1.000 |
| | |
| | |
| |Sig. (2-tailed) |
| |.751 |
| |.122 |
| |.000 |
| |.000 |
| | |
| | |
| | |
| |N |
| |975 |
| |975 |
| |975 |
| |975 |
| |975.000 |
| | |
|a) |0 |
|b) |1 |
|c) |2 |
|31 |William Kingdon Clifford once said, “The danger to society is not merely that it should believe wrong things, though that is |
| |great enough; but that it should become credulous, and lose the habit of __________ and inquiring into them; for then it must |
| |sink back into savagery.” |
|a) |analyzing results |
|b) |testing things |
|c) |studying statistics |
|32 |If Cohen’s d = .68, the effect size is… |
|a) |small |
|b) |medium |
|c) |large |
|33 |A researcher asks smokers (n = 10) and non-smokers (n = 10) to rate their health on a 9-point scale (higher numbers indicate |
| |better health). Their data are as follows. |
| |Smokers: M = 5.23, SD = 1.55 |
| |Non-smokers: M = 6.84, SD = 1.28 |
| |What is the approximate value of Cohen’s d? |
|a) |0.3 |
|b) |1.1 |
|c) |1.6 |
|34 |What is the approximate observed t-value for question #33? |
|a) |1.5 |
|b) |2.0 |
|c) |2.5 |
|35 |On a scale from 0 to 10, the average American reports a happiness level of 7.0. A sample of n = 64 students in PSY 211 report a|
| |happiness level of 6.2 (SD = 2.0). What is the observed t-value for this sample? |
|a) |3.0 |
|b) |3.2 |
|c) |3.4 |
|36 |Anxiety clients (n = 16) report their level of anxiety symptoms before and after a month of therapy, using the Beck Anxiety |
| |Inventory. Their level of anxiety falls by a few points (M = 5.0, SD = 4.0). What is the approximate observed t-value? |
|a) |1 |
|b) |4 |
|c) |5 |
Use the following between-group t-test Output to answer questions 37 through 40 (next page). Note that some sections of the Output are hidden.
|Group Statistics |
| |
| | |Levene's Test for |t-test for Equality of Means |
| | |Equality of Variances| |
| | |
|a) |1 |
|b) |2 |
|c) |3 |
|38 |Although it is hidden, what is the approximate t-value for the t-test involving regretfulness? |
|a) |1.3 |
|b) |1.5 |
|c) |1.7 |
|39 |What is the value for the degrees of freedom (df) for these t-tests? |
|a) |973 |
|b) |974 |
|c) |975 |
|40 |You meet a random person who is not employed. What is this individual most likely to be like? |
|a) |Someone who spends time outdoors instead of reading. |
|b) |Someone who is depressed and spends all day thinking about past mistakes. |
|c) |Someone who is slightly troubled by economic hardships. |
|Study Guide |
|Exam #4 |
|PSY 211 |
Disclaimer:
• This is a guide of the main points that I consider to be important. You are responsible for all material covered in the book or in lecture, unless otherwise noted by me.
Formulas:
• You will be given a formula sheet (attached) and the t-table from the book.
Not on this Exam:
• Do not use the formulas or d values in the book. Particularly, for the t-test, we used some simplified version of the formulas in class, which are easier, and still provide a close estimate of the longer formulas
• There are no story problems based on the one-tail t-test, you just need to know how it differs from a two-tail test.
Suggested Learning Strategies:
• Study in small groups
• Ask questions or e-mail Mike
• Know how to do all homework and study guide problems
• Make up your own multiple choice questions
Conceptual Questions:
• * Be able to interpret Output and work with results written in APA style (mainly t-tests, but correlation and regression Output are also fair game)
• * Be able to understand and define the differences between the z-test and the three types of t-tests. Given a story problem or list of data, be able to correctly identify which test to use.
• Know the four basic steps of hypothesis testing
• When writing out the null and alternative hypotheses, are we describing the expected difference in the sample or population?
• Know the difference between t-obtained and t-critical
• Know how probability relates to hypothesis testing
• How does the shape of the t-distribution differ from the shape of the z-distribution?
• How does sample size impact the critical t-value?
• What are degrees of freedom (df)?
• Why is it difficult to draw conclusions about group differences based on visual inspection of the data (such as, histograms)?
• What does a significant t-value mean?
• What does p = .000 really mean in the SPSS Output?
• Why is it possible for a result with a large effect size to be unreliable (not statistically significant)?
• Why is it possible for a small effect size to be reliable (statistically significant) in some cases?
• Know the main differences between the between-group and within-subject t-test
• Skepticism
Calculations:
• * Given r, r2, or d, be able to indicate the effect size
• Be able to calculate Cohen’s d, z-values, and various t-values given formulas
• Range of possible values for r, r2, and d
• If an obtained t-value is blacked out from SPSS Output, know how to calculate it from the remaining variables in the Output
Terms (may appear in multiple choice or short-answer):
• * p < .05
• Hypothesis testing
• Null hypothesis
• Alternative hypothesis
• Effect size
• Sampling error
• Iatrogenic
• Alpha (or significance) level
• Critical region
• Type I error
• Type II error
• Power
• One-tail vs. two-tail t-test (know the difference, but you won’t need to do any story problems based on one-tail tests)
• Pre-post study
• Manipulation check
• Matched sample
• Carryover effect
Formulas
I will also give you the t-table from the book!
You do not need to print them in advance to bring to the exam.
Beware, that in story problems, I might use “SD” as a symbol for standard deviation,
or “SE” to represent standard error of the mean.
Z = (M – μ) where σM = σ / [pic]
σM
Single sample t = (M – μ) where sM = s / [pic]
sM
Between-group t = [pic] where sM = [pic]
Cohen’s d for between-group t-test = [pic]
To find the value of s, average the standard deviation from each of the two subsamples, if available. If only the s for the combined sample is available, use that.
Within-subject t = MD / sMD where sMD = ([pic])
Cohen’s d for within-subject t-test d = MD / s
Old Exam Questions
I have taken these questions from last year’s exam. I think they will give you a good idea of the types of questions to expect, but ignore any that seem irrelevant! You can check answers here:
|3 |When writing the alternative hypothesis, researchers are describing differences that are expected to occur at this level |
|a) |sample |
|b) |construct |
|c) |population |
|4 |If SPSS shows that a correlation has a p-value of 0.12, the correlation is said to be |
|a) |statistically non-significant |
|b) |statistically significant |
|c) |not enough information |
|5 |If the alternative hypothesis is really correct, and based on sample data you reject the null hypothesis, you have made a |
|a) |Type I error |
|b) |Type II error |
|c) |correct decision |
|6 |A hypothesis that men and women do not differ on intelligence |
|a) |Null hypothesis |
|b) |Alternative Hypothesis |
|c) |One-tail hypothesis |
|8 |How will choosing a more strict alpha level impact the critical t-value? |
|a) |Increase it |
|b) |Decrease it |
|c) |No impact |
|9 |If Cohen’s d = - 4.39, the result will be significant |
|a) |Always |
|b) |Sometimes |
|c) |Never |
|10 |Type of t-test commonly used in twin studies |
|a) |single-sample |
|b) |between-group |
|c) |repeated-measures |
|12 |If the null hypothesis is really true, and your sample supports the alternative hypothesis, you have made a |
|a) |Type I error |
|b) |Type II error |
|c) |correct decision |
|13 |Effect size when Cohen’s d = .78 |
|a) |small |
|b) |medium |
|c) |large |
|14 |As sample size increases, the z value needed for significance will |
|a) |increase |
|b) |stay the same |
|c) |decrease |
|17 |Effect size when r2 = 0.26 |
|a) |small |
|b) |medium |
|c) |large |
|18 |Which of the following distributions is the flattest? |
|a) |z distribution |
|b) |t distribution where n = 5 |
|c) |t distribution where n = 10 |
|19 |The p-value shown in SPSS indicates the probability that |
|a) |the null hypothesis is true |
|b) |the alternative hypothesis is true |
|c) |the probability of a Type II error |
Below is the Output from a recent homework problem, in which you were to run two
t-tests, comparing gender differences in both “beauty concerns” and “war support,”
but some of the information has been removed. Use these charts for #21-22.
[pic]
[pic]
|21 |What is the value for the degrees of freedom? |
|a) |greater than 325 |
|b) |325 |
|c) |less than 325 |
|22 |What is the t-value for the “beauty concerns” t-test? |
|a) |greater than 2.37 |
|b) |2.37 |
|c) |less than 2.37 |
Below is some new Output, from our classroom data file, but not from any particular homework assignment. Instead of looking at gender differences, these t-tests examine differences across people who described themselves as an athlete (“Yes”) or not an athlete (“No”). I compared non-Athletes and Athletes along five variables: leadership, beauty concerns, physical complaints, authority problems, and life stress. These variables are very straightforward (no tricks), but I can answer questions if you want any details. Use these charts for #23-25 (next page).
[pic]
[pic]
|23 |How many of the five results shown are statistically significant? |
|a) |1 |
|b) |2 |
|c) |3 |
|24 |Based on these findings, if you met a random athlete, how might you expect them to differ from a non-athlete? |
|a) |More life stress |
|b) |More authority problems |
|c) |Fewer physical complaints |
|25 |What percentage of the sample self-reported that they were an athlete? |
|a) |less than 52.3% |
|b) |52.3% |
|c) |more than 52.3% |
|26 |Calculate a z-score, given the following information, and indicate whether it is | |
| |significant. | |
| | | |
| |Sample mean = 200 |z = |
| |Sample mode = 210 | |
| |Sample standard deviation = 160 | |
| |Population mean = 250 |Significant? yes/no |
| |Population mode = 248 | |
| |Population standard deviation = 111 | |
| |Sample size = 16 | |
| | | |
| | | |
| | | |
|28 |Psychologists have been fascinated by lottery winners. Using standard 9-point | |
| |happiness rating scales, they have tracked how their level of happiness changes after| |
| |winning. In fact, 1 year after winning the lottery, most winners (n = 9) note that | |
| |they are about 0.75 points happier (SD = 2.5). Calculate the within-subject t |t = |
| |statistic, Cohen’s d, and note whether the result is statistically significant. | |
| | |d = |
| | | |
| | | |
| | |Significant? yes/no |
More Old Exam Questions
Only review questions that appear relevant. Check out the answers online:
|1 |This statistic is not an example of an effect size |
|a) |p |
|b) |r |
|c) |d |
|2 |What is a hypothesis? |
|a) |Broad research question, aim, or goal motivating a particular study |
|b) |Detailed rationale explaining the logical basis for an observed finding |
|c) |Concise, testable statement describing the relationship between two variables |
|3 |Drug companies generally design drugs and then try to find a use for them at a later date. In one study, they examine whether a|
| |new drug impacts appetite. What type of hypothesis test should they use? |
|a) |No-tail test |
|b) |One-tail test |
|c) |Two-tail test |
|4 |What did William Kingdon Clifford say? |
|a) |“The danger to society is not merely that it should believe wrong things, though that is great enough; but that it should become|
| |credulous, and lose the habit of testing things and inquiring into them; for then it must sink back into savagery.” |
|b) |“But if we are empiricists, if we believe that no bell in us tolls to let us know for certain when truth is in our grasp, then |
| |it seems a piece of idle fantasticality to preach so solemnly our duty of waiting for the bell.” |
|c) |“It is better to be a human being dissatisfied than a pig satisfied, better to be Socrates dissatisfied than a fool satisfied. |
| |And if the fool or the pig are a different opinion, it is because they only know their own side of the question.” |
|5 |A null hypothesis states describes that there are no differences expected to occur at this level: |
|a) |measurement |
|b) |sample |
|c) |population |
|6 |Effect size for r2 = .26 |
|a) |small |
|b) |medium |
|c) |large |
|7 |The null hypothesis indicates: |
|a) |the effect will be negative, or opposite of expected |
|b) |an obtained difference will exceed chance |
|c) |no effect or no important difference |
|8 |Term indicating that results from any two particular studies might differ slightly due to chance: |
|a) |sampling error |
|b) |standard error of the mean |
|c) |carryover effects |
|9 |The results of a multiple regression indicate that R2 = .20, p = .50. Is this result statistically significant? |
|a) |non-significant |
|b) |significant |
|c) |not enough information |
|10 |Using a more strict alpha level for a z-test will cause the critical z-value to |
|a) |become more extreme |
|b) |stay the same |
|c) |become less extreme |
|11 |What type of test might you use to determine whether female doctors reliably differ from their romantic partners on IQ? |
|a) |correlation |
|b) |between-group t-test |
|c) |within-subject t-test |
|12 |What does a p-value describe? |
|a) |the probability that the result is reliable |
|b) |the probability that the result is due to chance |
|c) |the probability that the result will replicate |
|13 |Assume that the alternative hypothesis is accurate. If the researcher finds no effect, what has occurred? |
|a) |Type I error |
|b) |Type II error |
|c) |Iatrogenic error |
|14 |Effect size for Cohen’s d = .36 |
|a) |small |
|b) |medium |
|c) |large |
|15 |You have people rate how much they enjoy Coke and how much they enjoy Pepsi. The mean enjoyment rating for Coke is a bit higher|
| |than for Pepsi, and you find d = 1.25, t = 1.67, p = .63. How would you most likely get a result like this? |
|a) |large effect but a small sample |
|b) |unusual sample |
|c) |poor methodology or survey items |
|16 |This was not an example of a repeated-measured t-test discussed in class: |
|a) |Changes in tension before and after massage therapy |
|b) |Changes in physiological arousal before and after crossing an old bridge |
|c) |Changes in sleepwalking before and after sleep deprivation |
|17 |Which of the following distributions is the flattest? |
|a) |z distribution |
|b) |t distribution where n = 3 |
|c) |t distribution where n = 37 |
|18 |Effect size for r = .42 |
|a) |small |
|b) |medium |
|c) |large |
|19 |This type of test is not used to compare a treated sampled to an untreated population. |
|a) |z-test |
|b) |single-sample t-test |
|c) |between-group t-test |
|20 |There is no “depression gene” yet every year some researcher claims to have found it. The results are often reported on CNN and|
| |the other news networks, who fail to realize they are making this error. |
|a) |Type I error |
|b) |Type II error |
|c) |Hindsight bias |
|21 |Carefully examine the Output below for a series of between-group t-tests. The analyses compare “Early Birds” to “Night Owls” on|
| |five variables. Some information is missing or covered up. How many of the five results show a reliable group difference? |
| |[pic] |
| |[pic] |
|a) |1 |
|b) |2 |
|c) |3 |
|22 |Using the SPSS Output on the previous page, calculate the t-value for the group differences in Agreeableness, and choose the |
| |answer below closest to that t-value. |
|a) |1.3 |
|b) |1.7 |
|c) |2.1 |
|23 |Using the SPSS Output on the previous page, what would be the degrees of freedom for the analysis examining group differences in|
| |Neuroticism |
|a) |277 |
|b) |278 |
|c) |279 |
|24 |Study the following correlation table very carefully. The name of the first variable is blacked out. Based on the pattern of |
| |correlations, what might this variable be? |
| |[pic] |
|a) |depression |
|b) |ACT score |
|c) |happiness |
|25 |What do you suppose the value would be for the correlation in the “???” box? |
|a) |r = -.11 |
|b) |r =.02 |
|c) |r = .08 |
Part II. Calculations [10 points]
26. Z-test – 4 points
|Calculate a z-score, given the following information, and indicate whether | |
|it is significant. | |
| |Z = |
|Sample mean = 18 | |
|Sample mode = 22 | |
|Sample standard deviation = 10.75 |Significant? yes / no |
|Population mean = 20 | |
|Population mode = 16 | |
|Population standard deviation = 12.45 | |
|Sample size = 256 | |
| | |
27. t-test – 6 points
|28 people enroll in a clinical trail for a new schizophrenia medication. | |
|During the trial, ten patients drop out, and three more commit suicide. On| |
|a symptom rating scale, patients see an average reduction of 2.2 points (SD|t = |
|= 4.3) for their symptoms. Calculate the within-subject t-value. Indicate| |
|whether the result is significant. In a sentence or two, describe how you | |
|would interpret this finding. |Significant? yes / no |
| | |
| | |
| |Interpretation: |
| | |
| | |
Part III. Short Answer [10 points]
28. Pick One of the following:
a) List 5 types of inferential statistics and note when you would use each.
OR
b) List and briefly describe 5 major differences between the between-group and within-subject approaches.
OR
c) In a short paragraph, describe how inferential statistics are used in the social sciences. Make sure to mention the following terms: hypothesis testing, critical value, p-value, and effect size.
-----------------------
???
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.
Related searches
- photosynthesis study guide answers
- genesis study guide pdf
- 6th grade science study guide pdf
- biology 101 study guide printable
- ftce study guide pdf
- study guide for philosophy 101
- photosynthesis study guide quizlet
- science ged study guide 2019
- clep college composition study guide pdf
- study guide for photosynthesis pdf
- ged practice study guide pdf
- personal finance study guide pdf