Download Exam #3 Take Home Section Total Score (take home section): /30

Exam #3 Take Home Section
Total Score (take home section): /30 points
Resources you may use include open notes, any resources from class, and textbook/electronic
version. You may use the videos from my YouTube site. You may NOT use search engines
(Google, Yahoo, etc.) or other internet resources. All work must be your own with no help
from anyone else.
Use the “Exam 3 ANOVA.xlsx” file to complete this exercise.
In this example students were randomly assigned to one of three mnemonics (techniques for
improving memory) –
- rehearsal (the control group; simply repeat the words),
- visual imagery (form a mental image of what the word refers to), and
- peg method (memorize a rhyme, one is a gun, two is a shoe, three is a tree…. and associate
each word with the rhyming word).
They then saw a list of 20 words, one word every three seconds. They had to recall the words in
the same order that they appeared in the list. The number of words correctly recognized in the
proper order was recorded for each of the 15 participants in each of the three conditions.
Using an alpha significance level of .05, perform an Analysis of Variance (ANOVA). Instructions
below explain where to paste your output. Ensure you only paste in the pertinent SPSS output.
Note: I will deduct points if you paste excess output in your document – I want only what is
necessary to answer the question
1. Perform Step 1: Write the null and alternative hypotheses (write the hypotheses using the
equations and Greek letters form and state the hypotheses in sentence form). 2 points
H0: There is no relationship between memory and visual imagery (noting going on).
H1: There is relationship between memory and visual imagery.
H0: There is no relationship between memory and visual imagery memory techniques (nothing going on).
H1: There is relationship between memory and peg method memory techniques.
2. Step 2: Specify the level of risk (probability) of making a Type I error that we are willing
to accept: 1 point
The alpha level is .05, and is the probability of the type I error in statistics.
3. Step 3: Identify the test statistic 2 points
If the sample size (in this case there are 15 participants with 45 observations in each), then we will use the Ztest.
4. Step 4: State the Decision Rule using the p value approach (ensure you include the decision
rule in words, too). 2 points
If P is less than .05 then the null hypothesis has been rejected and there is no predictive value.
5. Step 5: Calculate the test statistic (using SPSS) and make a decision. For consistency for my
grading the exam, do the following:
a. Use the following value labels
• 1 = Rehearsal
• 2 = Imagery
• 3 = Peg
b. Use the “Exam 3 ANOVA.xlsx” data set and import, copy, or type your data into
SPSS. Ensure you set up your variables properly.
c. Use clear, understandable names for your group variable and your dependent variable.
6. Perform a one-way ANOVA using the options I used in class and the appropriate alpha
significance level from this scenario. Paste the pertinent output in this document where it is
stated. Reminder: I will deduct points if you paste excess output in your document – I want
only what is necessary to answer the question:
a. What are the mean and standard deviation for each of the groups (paste the appropriate
output below): 2 points
Rehearsal- SD = 4.25, mean=5.8
Imagery-SD= 3.94, mean=4.4
Peg-SD=3.19, mean= 16.8
b. What is the p value of the Levene’s test (paste the appropriate output below): 2 points
• Is Levene’s test significant?
1 points
The levene’s test is not significant since .722 is greater than our P-value of .005.
• What does that mean?
2 points
This means that our variances are not significantly different.
• What would it mean if you found the opposite answer to Levene’s test?
2 points
It would mean that the variances of the three groups are significantly different. This would mean
we had violated that assumption of homogeneity of variance.
c. Paste the ANOVA table below (please limit the numbers to no more than 3 decimal
places for each of the values): 2 points
d. Is your overall model significant and what does that mean? 2 points
Yes, because the P-value is less than .001, which is less than our alpha significance of .05. This means our
model has predictive value.
e. Run the post hoc tests I explained in class. Post the output to the post hoc tests below
(consider pasting as a jpeg so you can resize it to fit). 2 points
f.
What are the upper and lower values of Tukey’s HSD 95% confidence interval between
Imagery and Rehearsal? Interpret the confidence interval. 3 points
4.7875- upper
-1.9875- lower
95% of the time, the mean difference will be between-1.9875 and 4.7875. Since the confidence
interval spans “0”, then there is a good probability that the mean difference is equal to zero.
g. What are the upper and lower values of Bonferroni’s 95% confidence interval between
Imagery and Peg? Interpret the confidence interval. 2 points
-15.8770- lower
-8.9320- upper
This means that 95% of the time the mean difference will be between -15.8770 and 8.9320.
h. Why is the Least Significant Difference (LSD) confidence interval not a good approach
to use? 3 points
We use this method after the null has already been rejected.
7. BONUS (1 point extra credit: optional – not discussed in class): What is the R2 value?it
R2=SSm/SSt
.693=1383.6/1996
R2=.693
8. SUPER BONUS (2 points extra credit: optional – not discussed in class): What is the
Adjusted R2 value?
(1383.6)-(2*14.581)
1996+14.581
Adjusted R2 = 0.673655028