R&S 2 Final
Dr. Louis wants to know if blood lead levels influence IQ. They collect blood samples in 30 adults and divide them into three equal groups (n=10): low, medium, and high blood lead. Dr. Louis then administers the WAIS-III to each participant to measure IQ. Low Blood Lead Medium Blood Lead High Blood Lead T=988; M=98.8 T=896; M=89.6 T=791; M=79.1 SS1=380 SS2=76.1 SS3=120.8 -------------------------------------------------------------------------------------------------------------------------- N=30 G=2675 ∑ X2=241,041 ANSWER BOTH PARTS OF THIS QUESTION!! What is the value of η2 (i.e., the effect size)? Note: Round your answer to two decimal places. Is this a SMALL, MEDIUM, or LARGE effect size?
.77 large
In a study examining the effects of time of day (morning or afternoon) and temperature (cool, normal, warm) on worker productivity, how many interaction effects are possible?
1
What is the value for letter "B" in the source table? NOTE: ROUND YOUR ANSWER TO TWO DECIMAL PLACES!
1.25
When conducting a two-way ANOVA, there are ________ main effects and ______ interaction(s).
2; 1
What is the critical value?
3.01
What is the value for letter "C" in the source table? NOTE: ROUND YOUR ANSWER TO TWO DECIMAL PLACES!
4
How many subjects were there in the experiment?
5
Use the formula above to calculate the value of the test statistic. Show your work and round your answer to one decimal place.
5.3
Dr. Smith believes being raised by a depressed parent alters optimism. To test their hypothesis, Dr. Smith has two groups of students (five non-depressed and five depressed) take a measure of optimism and analyzes their scores. ANSWER BOTH PARTS OF THIS QUESTION! What are the degrees of freedom? **Report as an integer!!**
8, 2.306
Describe the difference between a one-way ANOVA versus a two-way ANOVA. Give a *DETAILED* example of each type including detailed descriptions of the independent and dependent variables involved in each one.
A one-way ANOVA has one independent variable. It allows you to compare multiple groups, usually three or more. There are usually three categorical groups. The means of the independent groups are being compared to the dependent variable. A good example would be to test out the best running shoe brands. A two-way ANOVA has two independent variables. It allows for the examiner to compare the means of the groups against the two independent variables. The examiner will then compare the effect of the two independent variables against the dependent variable and against each other. Each separate variable will have multiple of its own samples. A good example would be to compare worker productivity to weather and time of day (like the one above). One-way ANOVA: 1 IV (with any number of levels), 1 DV Two-way ANOVA: 2 IVs (each with any number of levels), 1 DV
Source df SS MS F p Between 3 150 50 4.20 <.05 Participants 7 112 16 Error 21 250 11.9 Total 31 What do the results of the pizza preference study indicate?
A significant difference exists in the preference scores for the four different pizza types.
Which of the following should be included in the Participants section?
ALL OF THE ABOVE
Discrete variables are to _____ as continuous variables are to _____.
ALL of the above are true
The "results" section should include all of the following EXCEPT:
An interpretation of the data.
Which two distributions have the same standard deviation but different means?
B
Why can't the calculated F value be less than 0?
Because F is a ratio of variances and variances cannot be negative.
Which two distributions have the same mean, but different standard deviations?
C
You want to know whether people in different regions of the country are equally likely to vote Democratic, Republican, Independent, or Libertarian in the next election. You would use a:
Chi-square goodness-of-fit test
What are the results of the analysis? (Gender)
Fail to reject the null hypothesis; gender does not have an influence on seating preference
What are the results of the analysis?
Fail to reject the null hypothesis; the die was fair.
Source df SS MS F p Between 3 150 50 4.20 <.05 Participants 7 112 16 Error 21 250 11.9 Total 31 TRUE or FALSE?? The null and alternative hypotheses for the pizza preference study are (respectively): H0: μ1 = μ2 = μ3 = μ4 AND HA: μ1 ≠ μ2 ≠ μ3 ≠ μ4
False
The nonparametric equivalent to the one-way repeated measures ANOVA is the _____ test.
Friedman
Which bar graph below is the correct representation of the results?
Graph D
The null hypothesis for a one-way randomized ANOVA states:
H0: μ1 = μ2 = μ3.
The alternative hypothesis for a one-way randomized ANOVA states:
HA: Not all μ's are =.
Imagine that you are interested in evaluating the effect of gender on performance in a statistics class. There are a few outliers, so rather than doing a parametric test, describe what nonparametric test you could do instead. (Note: you may need to transform the data from interval/ratio to another type.) Be clear what test statistic you would use to determine if a difference in performance based on gender identity exists. Lastly, describe what advantages and disadvantages the nonparametric test has versus doing a parametric t-test. *MAKE SURE TO ANSWER ALL PARTS OF THIS QUESTION*
I would use the Wilcoxon rank-sum W test because there are two groups male and female. We will be comparing the medians from those two groups (n1+n2=). I could also assume that are sample size is small, one class. Advantages of a parametric test: The tests can provide results that are skewed. It takes into account the levels of variability. They have better statistical power. They don't require data. Advantages of nonparametric test: Better access to the median. Can be used when the sample size is small. Can be used to analyze all types of data and outliers. Easy to understand with quick calculations. disadvantages of nonparametric test: Less efficient. Because the distribution is free, the results may not be accurate. disadvantages of parametric test: Aren't valid. The sample size can be big. Usually, they only have access to continuous data and results can be affected by outliers
Which of the following represents the correct order for the sections in an APA format paper?
Introduction, Method, Results, Discussion
Why is the repeated-measures ANOVA more powerful than the between-groups ANOVA?
It controls for differences related to individual subjects.
The nonparametric equivalent to the one-way between-subjects ANOVA is the _____ test.
Kruskal-Wallis
Rosemary is studying whether bird-watchers become better at recognizing birds after having studied birdsongs. She tests 5 bird-watchers on their ability to recognize 10 different birds, then has them study birdsongs, and then tests the same 5 bird-watchers on 10 new birds. What is the independent variable?
Level of birdsong study
A description of what was done in the experiment is to the _____ section as a summary of what was found is to the _____ section.
Method; Results
The distribution below is ________________, where A, B, and C are equal to the ___________, __________, and ____________, respectively.
Negatively skewed; mean, median, mode
Dr. Helpful is interested in determining whether altruism (unselfish concern for the welfare of others) is a socially learned behavior. He develops a video which included 10 examples of altruistic behavior and shows his video to a group of 20 undergraduate students. He also shows a control video of the same people not engaged in altruistic behavior to a different group of 20 undergraduate students. After watching the video, Dr. Helpful has each participant fill out a survey asking about how likely they would engage in five different types of altruistic behavior. In constructing his spreadsheet, Dr. Helpful assigns the number 1 to all freshman participants, 2 to all sophomores, 3 to all juniors, and 4 to all senior participants. What scale of measurement best describes the "year in school" variable?
Nominal
What TYPE of variable is Time of Day?
Repeated-measures
Which type of ANOVA was computed?
Repeated-measures one-way ANOVA.
Which of the following were included as an INDEPENDENT variable? Note: You may need to choose more than one answer.
Temperature of Room Time of Day
Source df SS MS F p Between 3 150 50 4.20 <.05 Participants 7 112 16 Error 21 250 11.9 Total 31 Using the output above, what is the correct statistical decision, assuming an alpha level of .05?
The calculated value of F is significant, reject the null hypothesis.
What is wrong with the graph below?
The mean values shown are not all correct.
You are conducting a Chi-square analysis and see that the observed frequencies are extremely close to the expected frequencies. What should you expect?
The p-value will not be smaller than .05. The null hypothesis will fail to be rejected. The Chi-square analysis will not be significant. Correct! ALL of the above options are TRUE.
Rosemary is studying whether bird-watchers become better at recognizing birds after having studied birdsongs. She tests 5 bird-watchers on their ability to recognize 10 different birds, then has them study birdsongs, and then tests the same 5 bird-watchers on 10 new birds. Rosemary created a bar graph (shown below) of her data. What is wrong with the graph she created?
The range is truncated.
Which of the following is NOT TRUE?
The standard deviation is the least sophisticated measure of variation and the least frequently used
When an inferential statistic like t is used, we calculate the probability that the null hypothesis is wrong. What does a very low probability of the null hypothesis mean?
There are probably differences between groups in the study.
Jason conducts an experiment, and finds that an observed t value = 2.97, which for a two-tailed test has a p-value of .014. What does this mean?
There is a 1.4% chance of finding an absolute value of t that is this size or larger if the null hypothesis is true.
ook at the graph that you selected to be the correct one for the previous question. Select the options below that are correct. Note: You may need to select more than one option.
There is a likely interaction between the variables Temperature of Room and Time of Day. There is a likely main effect of the variable Temperature of Room.
Look at the graph above and select each correct option. Note: You may need to select more than one answer.
There is a likely main effect of Variable A.
Look at the graph above and select each correct option. Note: You may need to select more than one answer.
There is a likely main effect of Variable A. Correct! There is a likely main effect of Variable B.
Look at the graph above and select each correct option. Note: You may need to select more than one answer.
There is a likely main effect of Variable B.
The null and alternative hypotheses are: H0: Gender does not influence seating preference.Ha: Gender does influence seating preference.
True
Rejecting H0 when we should have failed to reject it is a _____ error.
Type I
Failing to reject H0 when we should have rejected it is a _____ error.
Type II
A researcher decides to use the .01 level of significance rather than using the more conventional .05 level of significance. What type of error (Type I or Type II) is the researcher more likely to make? Why?
Type II. By making it harder to reject the null, the risk of making a Type II increases.
Scientists determine the probability of collecting their data for an experiment by chance alone. The p-value for a given experiment is an indication of how likely that data would be obtained if the independent variable had absolutely NO effect. Knowing this, explain why one cannot prove there is a difference between treatment groups and explain how our "confidence" that a real mean difference exists changes as the p-value gets smaller. (Hint: How does the risk of a Type I error change as the p-value changes?)
Well, a smaller p-value lowers the risk of a Type 1 error. Without the proof of a difference, we create a "false alarm" type problem i.e. Type 1 error. We may not be able to prove a difference because our groups overlap or maybe we don't have enough people. Also, going back to the first sentence, chance alone. By saying chance alone, I'm assuming that there was no random selection. That may mean that the results won't be an accurate number or represent the overall population correctly. Whatever conclusion the researchers come up with, will be at random. I can only assume by lower the p-value, we are trying to "curve" our results to match our prediction. We cannot "prove" that a real difference exists because there will always be the possibility that we obtained our data by chance. Because the p-value is a probability value, it can never equal zero. As the p-value gets smaller, our confidence that a difference really exists improves and decreases our likelihood of making a type I error.
Explain when it would be appropriate to use a t test versus a one-way analysis of variance. In your answer be sure to indicate what type of data can be used for each. Also indicate when and why it would be necessary to use post hoc tests.
You should use ANOVA when you are comparing more than two groups. You can also use ANOVA when you want to test a specific theory. You would use ANOVA to help you know how each group responded to your test. With an ANOVA, your null is usually the same, H0 = u1=u2=u3. You should use a t-test when you are comparing two groups. You also use a t-test when the population standard deviation is not given. Using a post hoc test will help show the difference between each group in the case of a more than two group study.
What analysis should you conduct to determine if the die is fair?
a Chi-square goodness-of-fit test
What analysis should you conduct to determine if the gender influences seating preference?
a Chi-square test of independence
Using designs with more than two levels of an independent variable allows researchers to:
accomplish all of these alternatives.
If between-groups variance is small, then we have not observed:
an effect of the independent variable.
The between-subjects F-ratio is a ratio of ____ variance over ____ variance.
between-treatment; within-treatment
What is the biggest problem with doing a repeated-measures ANOVA rather than a between-subjects ANOVA?
carry-over effects
It is necessary to know the shape of a distribution in order to:
choose the most appropriate measure of central tendency
All other things being equal, as the difference between sample means decreases, the calculated t statistic will:
decrease
Dr. Helpful is interested in determining whether altruism (unselfish concern for the welfare of others) is a socially learned behavior. He develops a video which included 10 examples of altruistic behavior and shows his video to a group of 20 undergraduate students. He also shows a control video of the same people not engaged in altruistic behavior to a different group of 20 undergraduate students. After watching the video, Dr. Helpful has each participant fill out a survey asking about how likely they would engage in five different types of altruistic behavior. In the above example, a participant's score on the Altruism survey is the:
dependent variable
Within-groups variance is comprised of __________variance.
error
All other things being equal, as standard deviation or standard error decreases, the calculated t statistic will:
increase
All other things being equal, as the sample size increases, the calculated t statistic will:
increase
Dr. Helpful is interested in determining whether altruism (unselfish concern for the welfare of others) is a socially learned behavior. He develops a video which included 10 examples of altruistic behavior and shows his video to a group of 20 undergraduate students. He also shows a control video of the same people not engaged in altruistic behavior to a different group of 20 undergraduate students. After watching the video, Dr. Helpful has each participant fill out a survey asking about how likely they would engage in five different types of altruistic behavior. In the above example, the video condition to which participants were assigned is the:
independent variable
The calculated F _____________ statistically significant. Therefore, the null hypothesis should be ________________.
is; rejected
A factorial design involves:
manipulating more than one independent factor (variable).
Compared to related-samples t-tests, independent samples t-tests have _______________ but don't have _______________.
more variability; potential carryover effects
Chi-square tests are to _____ data as Wilcoxon tests are to _____ data.
nominal; ordinal
No effect is to _____ hypothesis as effect is to _____ hypothesis.
null; alternative
Which p value would signify the most confident rejection of the null hypothesis?
p<.001
The distribution below is ________________, where A, B, and C are equal to the ___________, __________, and ____________, respectively.
positively skewed; mode, median, mean
A good hypothesis will always be ____________________.
testable
A significant F value tells us:
that differences exist between at least two groups, but does not tell us which groups or how many differences are significant.
Whenever the F-ratio is near 1.00 it means that:
the between-groups variation is no larger than would be expected by chance alone and no larger than the within groups variance.
Two variables interact when:
the effect of one independent variable depends on the level of the other independent variable.
Which of the following is NOT an assumption of the one-way repeated measure ANOVA?
the groups are independent
A main effect indicates:
the mean differences among the levels of one variable.
The larger the within-groups (error) variance:
the more difficult it becomes to show the effects of treatment variance.
Between-groups variance is comprised of __________ variance AND _____________ variance.
treatment; error
The null and alternative hypotheses are: H0: the probability of rolling each side of the die is the same HA: the probability of rolling each side of the die is not the same
true
The Brief Resilience Scale (BRS) is a self-rating questionnaire aimed at measuring an individuals' ability to "bounce back from stress". Scores on the scale can range from 1- 5. A score from 1.00-2.99 is considered low, from 3-4.30 is considered normal, and from 4.31-5.00 is considered high. Dr. Walker recently became interested in how well the BRS would measure resilience in women who have experience various forms of intimate partner violence (IPV). She collects data from four separate groups of women who have not experienced IPV (i.e., the control group, n=14), those who experienced only verbal abuse (n=11), those who experienced only physical abuse (n=12), and those who experienced both verbal and physical abuse (n=10). She obtained the results below.
1.) The types of IPV. There are four levels. 2.) The dependent variable is the BRS scale accuracy. The data is ordinal. 3.) Null u1=u2=u3, Alternative not all u's are equal. 4.) One-way-repeated-measures ANOVA. 5.) I would not say the results were significant because there's an even split between if we should reject or not. 6.) A post hoc test would be suitable because it would allow us to compare all groups to determine which ones differ significantly. 7.) I would say that the BRS scale did not provide good results. It was hard to tell whether or not to reject the null or not. It didn't help that each group had a different number of participants. That may have messed with the results.
Use the formula below to calculate the value of the test statistic. Show your work and round your answer to two decimal places. To get the expected frequencies for each cell use this formula: fe = fcfr/N (Gender)
1.54
What is the critical value? Recall that df = # of columns - 1. **Please round your answer to two decimal places.
11.07
Dr. Louis wants to know if blood lead levels influence IQ. They collect blood samples in 30 adults and divide them into three equal groups (n=10): low, medium, and high blood lead. Dr. Louis then administers the WAIS-III to each participant to measure IQ. Low Blood Lead Medium Blood Lead High Blood Lead T=988; M=98.8 T=896; M=89.6 T=791; M=79.1 SS1=380 SS2=76.1 SS3=120.8 What is the value of SS Between? Note: Round your answer to two decimal points!
1943.27
How many levels were there for the variable Time of Day?
2
In a study examining the effects of time of day (morning or afternoon) and temperature (cool, normal, warm) on worker productivity, how many main effects are possible?
2
Statistics Exam Scores at Different Times of Day and Temperature Temperature of Room Cool Normal Warm Time of Day Morning 100 57 10 Afternoon 55 57 53 How many independent variables were there?
2
In a study examining the effects of time of day (morning or afternoon) and temperature (cool, normal, warm) on worker productivity, the factorial notation would be:
2 x 3.
Dr. Helpful is interested in determining whether altruism (unselfish concern for the welfare of others) is a socially learned behavior. He develops a video which included 10 examples of altruistic behavior and shows his video to a group of 20 undergraduate students. He also shows a control video of the same people not engaged in altruistic behavior to a different group of 20 undergraduate students. After watching the video, Dr. Helpful has each participant fill out a survey asking about how likely they would engage in five different types of altruistic behavior. In this experiment n = ______ and N = _______.
20, 40
Dr. Louis wants to know if blood lead levels influence IQ. They collect blood samples in 30 adults and divide them into three equal groups (n=10): low, medium, and high blood lead. Dr. Louis then administers the WAIS-III to each participant to measure IQ. Low Blood Lead Medium Blood Lead High Blood Lead T=988; M=98.8 T=896; M=89.6 T=791; M=79.1 SS1=380 SS2=76.1 SS3=120.8 -------------------------------------------------------------------------------------------------------------------------- N=30 G=2675 ∑ X2=241,041 What are the values for MSBetween and MSWithin? Note: Round each answer to two decimal points and enter one value per blank in the order asked above.
21.37 971.63
Dr. Louis wants to know if blood lead levels influence IQ. They collect blood samples in 30 adults and divide them into three equal groups (n=10): low, medium, and high blood lead. Dr. Louis then administers the WAIS-III to each participant to measure IQ. Low Blood Lead Medium Blood Lead High Blood Lead T=988; M=98.8 T=896; M=89.6 T=791; M=79.1 SS1=380 SS2=76.1 SS3=120.8 -------------------------------------------------------------------------------------------------------------------------- N=30 G=2675 ∑ X2=241,041 What is the value of SS Total? Note: Round your answer to two decimal points!
2520.17
Dr. Louis wants to know if blood lead levels influence IQ. They collect blood samples in 30 adults and divide them into three equal groups (n=10): low, medium, and high blood lead. Dr. Louis then administers the WAIS-III to each participant to measure IQ. Low Blood Lead Medium Blood Lead High Blood Lead T=988; M=98.8 T=896; M=89.6 T=791; M=79.1 SS1=380 SS2=76.1 SS3=120.8 -------------------------------------------------------------------------------------------------------------------------- N=30 G=2675 ∑ X2=241,041 What are the values for dfBetween, dfWithin, and dfTotal? Note: Enter each value as an integer with one value per blank in the order asked above.
27 2 29
Dr. Louis wants to know if blood lead levels influence IQ. They collect blood samples in 30 adults and divide them into three equal groups (n=10): low, medium, and high blood lead. Dr. Louis then administers the WAIS-III to each participant to measure IQ. Low Blood Lead Medium Blood Lead High Blood Lead T=988; M=98.8 T=896; M=89.6 T=791; M=79.1 SS1=380 SS2=76.1 SS3=120.8 -------------------------------------------------------------------------------------------------------------------------- N=30 G=2675 ∑ X2=241,041 How many levels of the independent variable were in Dr. Louis's lead exposure experiment?
3
How many levels were there for the variable Temperature of Room?
3
Dr. Smith believes being raised by a depressed parent alters optimism. To test their hypothesis, Dr. Smith has two groups of students (five non-depressed and five depressed) take a measure of optimism and analyzes their scores. Given the following data, calculate t. **ROUND AND REPORT YOUR ANSWER TO TWO DECIMAL PLACES!!** Non-depressed: M1= 24, SS1 = 178 Depressed: M2 = 12, SS2=122
3.10
Dr. Louis wants to know if blood lead levels influence IQ. They collect blood samples in 30 adults and divide them into three equal groups (n=10): low, medium, and high blood lead. Dr. Louis then administers the WAIS-III to each participant to measure IQ. Low Blood Lead Medium Blood Lead High Blood Lead T=988; M=98.8 T=896; M=89.6 T=791; M=79.1 SS1=380 SS2=76.1 SS3=120.8 -------------------------------------------------------------------------------------------------------------------------- N=30 G=2675 ∑ X2=241,041 What was the critical value for Dr. Louis's lead exposure experiment? Note: Round your answer to two decimal places! HINT: If specific df is not listed in the table, use the next LOWER value.
3.37
Dr. Smith believes being raised by a depressed parent alters optimism. To test their hypothesis, Dr. Smith has two groups of students (five non-depressed and five depressed) take a measure of optimism and analyzes their scores. Given the following data, calculate sM1-M2. **ROUND AND REPORT YOUR ANSWER TO TWO DECIMAL PLACES!!** Non-depressed: M1= 24, SS1 = 178 Depressed: M2 = 12, SS2=122
3.87
Dr. Smith believes being raised by a depressed parent alters optimism. To test their hypothesis, Dr. Smith has two groups of students (five non-depressed and five depressed) take a measure of optimism and analyzes their scores. Given the following data, calculate s2p. **ROUND AND REPORT YOUR ANSWER TO TWO DECIMAL PLACES!!** Non-depressed: M1= 24, SS1 = 178 Depressed: M2 = 12, SS2=122
37.5
Dr. Louis wants to know if blood lead levels influence IQ. They collect blood samples in 30 adults and divide them into three equal groups (n=10): low, medium, and high blood lead. Dr. Louis then administers the WAIS-III to each participant to measure IQ. Low Blood Lead Medium Blood Lead High Blood Lead T=988; M=98.8 T=896; M=89.6 T=791; M=79.1 SS1=380 SS2=76.1 SS3=120.8 -------------------------------------------------------------------------------------------------------------------------- N=30 G=2675 ∑ X2=241,041 What is the value of F? Note: Round your answer to two decimal places.
45.47
How many treatment were given in the experiment?
5
What is the value for letter "A" in the source table? NOTE: ROUND YOUR ANSWER TO TWO DECIMAL PLACES!
5
What is the critical value? Recall that df = (# of columns - 1)(# of rows - 1). *Round your answer to two decimal places. (Gender)
5.99
Dr. Louis wants to know if blood lead levels influence IQ. They collect blood samples in 30 adults and divide them into three equal groups (n=10): low, medium, and high blood lead. Dr. Louis then administers the WAIS-III to each participant to measure IQ. Low Blood Lead Medium Blood Lead High Blood Lead T=988; M=98.8 T=896; M=89.6 T=791; M=79.1 SS1=380 SS2=76.1 SS3=120.8 -------------------------------------------------------------------------------------------------------------------------- N=30 G=2675 ∑ X2=241,041 What is the value of SS Within? Note: Round your answer to two decimal points!
576.9
TRUE or FALSE?? A researcher hypothesizes that children who learn to read using phonics will read at a different level than those not taught in this manner. The appropriate statistical hypothesis are: NULL → H0: μphonics ≠ μno phonics ALTERNATIVE → H1: μphonics = μno phonics
False
Use the source table above to answer this question. TRUE or FALSE?? The ANOVA table above indicates there is a significant main effect of Time of Day and a significant Temperature of Room x Time of Day Interaction. The main effect of Temperature of Room is NOT significant.
False
What is the only measure of central tendency that you can calculate when you have nominal data?
Mode
Rosemary is studying whether bird-watchers become better at recognizing birds after having studied birdsongs. She tests 5 bird-watchers on their ability to recognize 10 different birds, then has them study birdsongs, and then tests the same 5 bird-watchers on 10 new birds. What is the dependent variable?
Number of correctly identified birdsongs
___________ is to identity and magnitude as ____________ is to identity, magnitude, equal unit size, and a true zero.
Ordinal scale; ratio scale
Dr. Smith believes being raised by a depressed parent alters optimism. To test their hypothesis, Dr. Smith has two groups of students (five non-depressed and five depressed) take a measure of optimism and analyzes their scores. Below is the output of the analysis.
Reject the null hypothesis; being raised by a depressed parent alters optimism.
Using the output above, what is the correct statistical decision, assuming an alpha level of .05?
Reject the null hypothesis; the study of birdsongs changes bird identification performance.
Eight participants were recruited and asked to give their preference for four different pizza types (plain, sausage, pepperoni, and deluxe). Preference scores ranged from 0-10, with 0 indicating the lowest preference score and 10 indicating the highest preference score. The results of the analysis are presented below.
Repeated-measures
What TYPE of variable is Temperature of Room?
Repeated-measures
Many students experience text anxiety that interferes with their academic performance. Suppose a college counselor hypothesized that listening to relaxing music before an exam would reduce this anxiety. Describe an experiment using two groups that could be conducted to test the counselor's hypothesis. In your answer be sure to describe the design (i.e., between- or within-subjects), describe the treatment difference between the two groups (i.e, control vs. experimental group), indicate how many participants you would use (i.e., n), idicate how many total observations you would have (i.e., N), and indicate how the data would be analyzed (i.e., what type of t-test).
The study would have 40 participants all freshmen that will divide into two groups. It would be a between-subject design. Each group will have 20 students all randomly selected. My first group (A) would be the control group. I would have them study and test like normal without music. My second group (B) would be the experimental group. I would have them study and test with classical music or whatever relaxing music they choose. It would be an independent sample t-test. I would like the experiment to run through the entire first semester. That way we will get a feel of the change in confidence levels throughout the semester as well.
Look at the graph above and select each correct option. Note: You may need to select more than one answer.
There is a likely main effect of Variable A. Correct! There is a likely main effect of Variable B. Correct! There is a likely significant A x B interaction.
Look at the graph above and select each correct option. Note: You may need to select more than one answer.
There is a likely main effect of Variable A. Correct! There is a likely significant A x B interaction.
Look at the graph above and select each correct option. Note: You may need to select more than one answer.
There is a likely main effect of Variable B. Correct! There is a likely significant A x B interaction.
Look at the graph above and select each correct option. Note: You may need to select more than one answer.
There is a likely significant A x B interaction.
Why do we calculate Analysis of Variance (ANOVA) when we have more than two treatment means instead of just doing multiple t-tests?
To prevent an inflation in the risk of a Type I error.
Dr. Louis wants to know if blood lead levels influence IQ. They collect blood samples in 30 adults and divide them into three equal groups (n=10): low, medium, and high blood lead. Dr. Louis then administers the WAIS-III to each participant to measure IQ. Low Blood Lead Medium Blood Lead High Blood Lead T=988; M=98.8 T=896; M=89.6 T=791; M=79.1 SS1=380 SS2=76.1 SS3=120.8 -------------------------------------------------------------------------------------------------------------------------- N=30 G=2675 ∑ X2=241,041 TRUE or FALSE? The results of Dr. Louis's lead exposure experiment were statistically significant. The level of lead exposure does affect performance on the WAIS-III.
True
Dr. Helpful is interested in determining whether altruism (unselfish concern for the welfare of others) is a socially learned behavior. He develops a video which included 10 examples of altruistic behavior and shows his video to a group of 20 undergraduate students. He also shows a control video of the same people not engaged in altruistic behavior to a different group of 20 undergraduate students. After watching the video, Dr. Helpful has each participant fill out a survey asking about how likely they would engage in five different types of altruistic behavior. To determine if there is a difference between the participants in the video conditions, Dr. Helpful needs to calculate:
an independent-samples t-test
In a _____________ design each participant receives only one treatment condition, while in a ______________ design each participant receives every treatment condition.
between-participants; repeated-measures
Wilcoxon rank-sum test is to _____ as Wilcoxon matched-pairs signed-ranks T test is to _____.
between-subjects design; within-subjects design
The distribution above is ____________________. A and B represent _______________, while C and D represent the ___________ and ____________, respectively.
bimodal; the modes, mean, median
The "method" section:
is complete if it meets the "criterion of replication."
Dr. Louis wants to know if blood lead levels influence IQ. They collect blood samples in 30 adults and divide them into three equal groups (n=10): low, medium, and high blood lead. Dr. Louis then administers the WAIS-III to each participant to measure IQ. Low Blood Lead Medium Blood Lead High Blood Lead T=988; M=98.8 T=896; M=89.6 T=791; M=79.1 SS1=380 SS2=76.1 SS3=120.8 -------------------------------------------------------------------------------------------------------------------------- N=30 G=2675 ∑ X2=241,041 Dr. Louis's data on lead exposure were collected using a _____-way, _________-subjects design.
one; between
Rosemary is studying whether bird-watchers become better at recognizing birds after having studied birdsongs. She tests 5 bird-watchers on their ability to recognize 10 different birds, then has them study birdsongs, and then tests the same 5 bird-watchers on 10 new birds. Which type of design is Rosemary using?
paired-samples t test
Suppose you tested two groups of subjects on speed of learning a new task. One group had a mean of 9 trials, and the other group had a mean of 11 trials. Your independent groups t statistic was not significant. What accounts for the difference between the means?
sampling error
Post hoc tests are necessary after an ANOVA when the test is ____ and there are ____ or more groups being compared.
significant; 3