PSYC 2100 sec 01-06Spring 2018: Exam 1 Extra Assignment
* Anyone in the class can do this assignment regardless of exam 1 score.
* The assignment consists of 20 even-numbered questions from a PREVIOUS edition of the text, which do not have answers provided for them. You are encouraged to use YOUR text's odd-numbered questions and their solutions in the back of the book, as well as the examples in the chapters, as models of how to answer the assigned items. Items will be worth 0.5 points each.
* Maximum number of points to gain is 10, with these exceptions: 1) Maximum TOTAL number of points on the exam is still 40, so if you got 37 you only have 3 points to gain - and to get those 3 points you still must complete the whole assignment, not just 30% of it! 2) A score of 10 guarantees an exam 1 score corresponding to least a "C" grade, regardless of initial score on the exam.
* YOU CAN USE YOUR TEXT AND LECTURE NOTES (and you may have to consult them more carefully now!).
* YOU CANNOT WORK TOGETHER ON THE ASSIGNMENT - THAT WILL BE CONSIDERED CHEATING! Remember, it's an exam, not just homework. FYI, the typical operational definition of cheating is a striking pattern of identical incorrect calculations and answers. If you cheat but get everything correct, you may not be detected, but the knowledge of what a bad person you are will eat at your soul till your dying day and family and friends will turn away from you and animals will smell your foulness and you'll wish you had just accepted a possibly slightly lower grade based on your own work. BE A GOOD PERSON.
* I will ease my scoring task by using a set of multiple choice alternatives for these questions, and a bubble sheet that the computer center can score for me. Bubble sheets will be passed out in class, but there's absolutely no need to wait for them before completing this assignment. You can bubble in your 20 answers later if you don't have a bubble sheet. The only ID information I need bubbled in is your LAST NAME and FIRST NAME in that order, and your accurate 7-digit StudentAdmin/PeopleSoft ID.
* Turn in BOTH the assignment with all work NEATLY written out or typed where possible, along with the corresponding bubble sheet that I'll pass out to you.
* DUE DATE is Thursday 3/8/18 though of course you should complete it immediately so as not to let it conflict with any exam studying! If you don't have it in class on the due date you can put it in my mailbox. Don't skip class that day to finish this, that would be considered lame -- there is no need, and you'd be missing important in-class information for the upcoming exam!
* Please LEARN this stuff as you do it, it's the only reason I'm offering this assignment and all these topics will be fair game on exam 2 anyway.
SOME USEFUL FORMULAS
One-way ("goodness of fit") Chi-Square 2 = [(fO-fE)2/fE] with df = no. of categories -1
Two-way ("test for independence") Chi-Square 2 = [(fO-fE)2/fE] with df = (R-1)(C-1) and expected frequencies fE = fCOLfROW/N
Effect size for test of independence = (2 / N); Cramér's V = (2 / (N df*)) with df* = smaller of R-1 or C-1
Population: mean = , variance = 2 , standard deviation = , size = N
Sample: mean = M , variance = s2 , standard deviation = s , size = N, df = N-1
Sum of Squares (of deviations from the mean): SS = (X-M)2 = (X-M)(X-M)
Population Variance = 2 = SS/N = (X-)2 / N
Sample Variance: s2 = SS/df = (X-M)2 / (N-1)
Standard Deviation = variance
z = (X-)/ in population or z = (X-M)/s in sample
X = + z() in population or X = M + z(s) in sample
Read each question and all the alternatives carefully. Circle the letter of the BEST answer on this sheet, and fill in the corresponding bubble on your bubble sheet.
Questions on Chapter 1:
1.It is known that the population of laboratory rats reaches an average weight of 510 grams at age 6 months. To test the effectiveness of a new growth hormone, a researcher selects a sample of 10 newborn rats and injects each rat with the hormone. Six months later, the rats in the sample are weighed and the researcher finds an average weight of 528 grams. Based on these results, can the researcher conclude that the growth hormone had an effect on the rats in the sample? Explain why or why not. (Hint: If the hormone had no effect, how can you explain the difference between the sample average and the population average?)
a.the hormone had the effect of adding 18g to the rats' weight
b.the hormone had the effect of adding something to the rats' weight but we don't know exactly how much
c.the hormone might have no effect on the rats' weight since the 18g difference could be entirely due to sampling error
d.the hormone definitely has no effect on the rats' weight since 18g is not a large enough amount to consider as a real difference
2.A researcher reports that individuals who survived one heart attack and were given daily doses of aspirin were significantly less likely to suffer a second heart attack than survivors who were given an inactive placebo instead of aspirin. For this study, identify the independent variable and the dependent variable.
a.IV: whether the person has a second heart attack; DV: aspirin vs. placebo
b.IV: aspirin vs. placebo; DV: whether the person has a second heart attack
c.IV: whether the person has a first heart attack; DV: whether the person has a second heart attack
d.IV: aspirin; DV: placebo
3.A recent report indicates that elderly drivers (over 65 years old) are more likely to be injured in an automobile accident than are younger drivers. Is this study an experiment? Explain why or why not.
a.no - we didn't cause them to have accidents
b.no - we didn't randomly assign them to be older or younger
c.yes - we are studying the effect of age on likelihood of injuries
d.yes - the experiment includes an IV and DV and an operational definition of "elderly"
4.Three researchers are evaluating taste preferences among three leading brands of cola. After participants taste each brand, the first researcher simply asks each participant to identify his/her favorite. The second researcher asks each participant to identify the most preferred, the second most preferred, and the least preferred. The third researcher asks each participant to rate each of the colas on a 10-point scale, where a rating of 1 indicates “terrible taste” and 10 indicates “excellent taste.” Identify the scale of measurement used by each researcher.
I think there's some ambiguity in this question, so to be clear, let's assume that instead of calling one the "favorite", the first researcher asks participants to identify each cola as "same" or "different" from the others (maybe by giving them the same or different letter or number code); and again, just to be clear, let's assume that the third researcher believes the difference betweeen a rating of 4 and 6 is the same as the difference between a 6 and 8.
a.nominal; ordinal; interval
b.interval; ordinal; nominal
c.nominal; interval; ordinal
d.ordinal; interval; ratio
Questions on Chapter 2:
5.If it is appropriate to use a histogram to show the frequency distribution for a set of scores, would it also be appropriate to show the same set of scores in a bar graph?
No explanation required, just yes or no.
a.yes
b.no
c.pony
d.shnah
6.Complete the following frequency distribution table, and find each of the percentiles and percentile ranks requested:
X / f / cf / c%12 / 5
11 / 7
10 / 4
9 / 3
8 / 0
7 / 1
What is the 20th percentile?
a.10
b.9
c.8
d.7
Questions on Chapter 3:
7.Find the mean, media, and mode for the set of scores in the following frequency distribution table:
X / f5 / 2
4 / 5
3 / 3
2 / 2
1 / 2
The mean, median, and mode, respectively, would be:
a.mean = 3.21; median = 3.5; mode = 4
b.mean = 9; median = 3.5; mode = 4
c.mean = 9; median = 4; mode = 3.5
d.mean = 3.21; median = 4; mode = 3.5
8.A population of N = 8 scores has a mean = 12. What is the value of X for this population?
a.1.5
b.20
c.84
d.96
9.A sample of n = 10 scores has a mean of 7. If a new score of X = 18 is added to the sample, what will be the new value for the sample mean?
a.8.0
b.8.8
c.9.78
d.6.36
10.For each of the following situations, identify the measure of central tendency (mean, median, or mode) that would provide the best description of the “average” score:
A. A researcher asks each individual in a sample of 50 adults to name his/her favorite season (summer, fall, winter, spring)
B. An insurance company would like to determine how long people remain hospitalized after a routine appendectomy. The data from a large sample indicates that most people are released after 2 or 3 days but a few develop infections and stay in the hospital for weeks.
C. A teacher measures scores on a standardized reading test for a sample of children from a middle-class, suburban, elementary school.
Your answers for parts A, B, and C respectively would be:
a.(A) median; (B) mode; (C) mean
b.(A) mode; (B) median; (C) mean
c.(A) mode; (B) mean; (C) median
d.(A) median; (B) mean; (C) mode
Questions on Chapter 4:
11.A. A sample of n = 6 scores has SS = 60. What is the variance for this sample?
B. A population of N = 6 scores has SS = 60. What is the variance for this population?
Your answers for parts A and B respectively would be:
a.(A) 10; (B) 12
b.(A) 12; (B) 10
c.(A) 360; (B) 300
d.(A) 300; (B) 360
12.For the following scores:1, 0, 4, 1
A. Calculate the mean. (Note that the value of the mean does not depend on whether the set of scores is considered to be a sample or a population.)
B. Find the deviation for each score, and check that the deviations sum to zero.
C. Square each deviation, and compute SS. (Again, note that the value of SS is independent of whether the set of scores is a sample or a population.)
Your answers for parts A, B, and C respectively would be:
a.(A) 1.5; (B) 0; (C) 9
b.(A) 1.5; (B) 0; (C) 3.5
c.(A) 1.5; (B) 0; (C) 5
d.(A) 0; (B) 1.5; (C) 6.75
13.Calculate SS, variance, and standard deviation for the following population of N = 6 scores: 5, 0, 9, 3, 8, 5. (Note: The definitional formula for SS works well with these scores.)
The SS, variance, and standard deviation respectively would be:
a.54; 10.8; 3.29
b.14; 2.33; 1.53
c.14; 2.8; 1.67
d.54; 9; 3
Questions on Chapter 5:
14.For a population with = 60, a score of X = 52 corresponds to a z-score of z = –2.00. What is the standard deviation for this distribution?
a.8
b.1.0
c.4
d.2
15.In a distribution of scores, a raw score of X = 43 corresponds to z = 1.00 and a score of X = 49 corresponds to z = 2.00. Find the mean and the standard deviation for the distribution of scores.
The mean and standard deviation respectively are:
a.37; 3
b.37; 6
c.46; 3
d.46; 6
16.Suppose that you have a score of X = 55 on an exam with = 50. Which standard deviation would give you the better grade: = 5 or = 10?
Choose between 5 or 10 please:
a.5
b.10
c.70,809
d.a platypus
17.A population consists of the following scores: 12, 1, 10, 3, 7, 3
A. Compute and for the population.
B. Find the z-score for each raw score in the population.
C. Transform each score into a new standardized value so that the standardized distribution has a mean of = 100 and a standard deviation of = 20.
Do parts A, B, and C, and then from part C, choose which new score would correspond to the original score of 12:
a.115
b.120
c.130
d.140
Questions on Chapter 17:
18.A researcher would like to determine whether any particular age group has a greater risk of influenza-related death. A sample of 50 such cases is categorized according to the victim’s age. The observed frequencies are as follows:
UNDER 3030-60OVER 60
5540
Note that in the city from which the sample was selected, 30% of the population is in the “under 30” bracket, 40% is in “30-60” and 30% is in “over 60.” This information should be used in determining expected frequency values, since they cannot be based on equal expected frequencies of 1/3 (33%) in each age category. Can the investigator conclude that risk differs with age? Test with the .05 level of significance.
What is the value of chi-square that you calculated?
a.0.25
b.5.99
c.48.99
d.59.58
19.Last fall a college installed a new email system and conducted a series of training sessions to teach students and staff how to use the system. In the spring semester, the college used a survey to determine the level of satisfaction with the new system. In addition to measuring satisfaction, the survey asked whether or not each individual had attended a training session. The results of the survey are as follows:
VERYSOMEWHATSOMEWHATVERY
SATISFIEDSATISFIEDDISSATISFIEDDISSATISFIED
ATTENDED TRAINING153555
DID NOT ATTEND5453515
Use a chi-square test to determine if a person's level of satisfaction depends on whether they attended the training. In calculating the chi-square value, what is the expected frequency for people who attended the training and are "somewhat satisfied" with the system?
a.25
b.30
c.35
d.40
20.As part of a campaign to demonstrate sex discrimination in salary within the county government, a sample of n = 200 employees was selected, and each individual’s salary was recorded. The median salary was computed for the sample and each individual was classified by gender and relationship to the median. The obtained distribution was as follows:
FEMALEMALE
ABOVE MEDIAN2872
BELOW MEDIAN5248
Do these data indicate that the salary distribution for females is significantly different from the distribution for males? Test at the .05 level of significance. Also indicate what df were used for the test.
a.Yes, you reject the null hypothesis of "no salary discrimination"; df = 1
b.No, you fail to reject the null hypothesis of "no salary discrimination"; df = 1
c.Yes, you reject the null hypothesis of "no salary discrimination"; df = 3
d.No, you fail to reject the null hypothesis of "no salary discrimination"; df = 3