Help with homework
Statistics
Summer 2019
Name: Cindy Charles
Multiple choice section:
1. A researcher is interested in studying the eating behavior of a rats and selects a group of 25 rats to be tested in a research study. The group of 25 rates is an example of a a. sample . b. statistic c. population d. parameter
2. A researcher uses an anonymous survey to investigate the study habits of the American college students. The entire group of American college students is an example of a a. sample . b. statistic c. population d. parameter
3. A characteristic, usually a numerical value, that describes a sample is called a a. sample . b. statistic c. population d. parameter
4. Determining the class standing for the graduating seniors at a high school would involve measurement on a(n) ____________ scale of measurement. a. nominal . b. ordinal c. interval d. ratio
5. A researcher conducts a study to determine whether moderate doses of St. John’s Wort have any effect on memory in college students. For this study, with is the independent variable?
a. the amount of St. John’s Wort given to each participant.
b. the memory score for each participant
c. the group of college students
d. cannot answer without more information.
6. When we are interested in simply looking at the association or relationship between two contiguous variables as they exist naturally , the following research method is likely to be helpful: a. correlational b. experimental c. quasi-experimental d. non-parametric
7. In an experiment looking at the effect of eating varied levels of multiple portions of ice cream, daily, on blood serum cholesterol levels (HDL) a. eating ice cream is the independent variable (IV) and HDL is the dependent variable (DV). b. ice cream, the DV and HDL, the IV c. neither, this is a correlational study d. ice cream and HDL are both independent variables
8. “Girl, boy, girl, girl, boy, boy, boy, girl. So, there’s 4 girls and 4 boys.” Our enumerator is employing which of the following scales a. ratio b. sex differential c. interval d. nominal
9. “I came in first place in the “Best Statistics Professor” category. That clearly shows I am much better at this than most other professors on campus.” a. This is a reasonable conclusion, since first place in Statistics must be a higher rating than, say, third place in Multicultural Education. b. The speaker mistakenly attributes arithmetic characteristics to ordinal data. c. The statement has absolutely no meaning, since we do not know the number of other professors on campus or teaching statistics. It represents an example of the absolute or ratio scale. d. The interval scale applies here, because voters used a relative standard.
10. Celsius, Fahrenheit, & IQ scales are a. ratio scales b. interval scales c. not similar scales of measurement d. ordinal scales
11. Kelvin, height, weight and speed are a. ratio scales b. interval scales c. not similar scales of measurement d. ordinal scales
12. You are instructed to subtract four points from each score and find the sum of the resulting values. How would this set of instructions be expressed in summation notation
a. ∑ X-4
b. ∑ (X-4)
c. 4- ∑ X
d. ∑ (4-X)
13. A distribution of reading scores produced by a diagnostic test spreads the raw scores of lowest performing students across a broad range of scores for further differentiation, while grouping the highest performing students’ raw scores along a higher, but much narrower range of scores. The resulting distribution is best characterized as a. positively skewed b. platykurtic c. negatively skewed d. percentile-like
14. Of the mean, median or mode, which, in your judgment, is best used to characterize central tendency of the following distribution of scores 86, 59, 3005, 99, 32, 18, 32, 18, 18.
a. mean
b. median
c. mode
d. none can be used to characterize central tendency
15. The relationship between population variance and standard deviation is a. factorial b. syntonic c. collaborative d.multiplicative
16. A z-score of zero a. indicates an error in calculations, failure to square the deviations b. is only theoretically possible c. is the mean d. is obtained by correlation of scores
17. Z-scores are a. correlational variables b. used with population score c. have a standard deviation of 2. d. are an example of non-parametric data
18. What Z-score value separates the top 10% of a normal distribution from the bottom 90%? Z =
a. 1.28
b. 0.25
c. -1.28
d. -.25
19. A jar contains 10 red marbles and 30 blue marbles. A random sample of n = 3 is selected from the jar. If the first two marbles are both blue, what is the probability that the third marble will be red?
a. 10/3
b. 10/38
c. 10/40
d. 8/38
20. Which of the following are requirements of a random sample?
a. Every individual has an equal chance of being selected.
b. The probabilities cannot change during a series of selections
c. There must be sampling with replacement
d. All of the above
21. The corresponding standard score value of a z-score of -3 for a population of scores with a mean of a 100 and a standard deviation of 15 would be a. 55 b. 82 c. 145 d. 130
22. What is the value of SS for the following set of scores? Scores 0, 1, 4, 5
a. 17
b. 18
c. 42
d. 10
23. Which set of scores has the smallest standard deviation?
a. 11, 17, 31, 53
b.5, 11, 42, 22
c. 145, 143, 147, 145
d. 27, 105, 10, 80
24. If you are interested in cutting back on caloric intake and losing weight, you would be striving for
a. A positive correlation between caloric intake and weight
b. An inverse correlation between caloric intake and weight
c. A negative correlation between caloric intake and weight
d. I don’t know so I’ll just exercise like crazy.
25. Which of the following is a perfect correlation/
A. .00
B. -1.00
C. .9999
D. NONE OF THE ABOVE
26. If you are interested in the association between percentile rank in high school and percentile rank in college, you should use
a. Continuous data
b. Pearson correlation
c. Spearman correlation
d. Orthogonal factor analysis
27. When a correlation (say between hours of study and grades for the top 10% of students in school) does not have a full set of values (a restricted range), we
a. Should have confidence in the prediction as long as there is no violation of a priori hypothesis
b. Should consider that the restricted range might overstate the relationship
c. Should consider that the restricted range might understate the relationship
d. Do not have consider the restricted range issue because of the continuous values of GPA.
28. The best fitting straight line for a data set of X-values plotted against y-values is called
a. a correlation matrix
b. polynomial expansion
c. varimax rotation
d. a regression equation
Short answer section
1. You toss a penny in the air 15 times and get 15 heads in a row. What is the likelihood that heads comes up on the sixteen toss, assuming a non-biased coin? Cite and explain a relevant principle in justifying your answer.
2. When the mega-million jackpot reaches $100 million dollars, the lines at my local deli seem to grow exponentially. Why are you more likely to be shot and wounded during a robbery attempt at the deli, then you are to win the jackpot? What advice would you give to someone who spends $75 per week on lottery tickets?
1. Problem section
2. A special needs teacher records the number of trials it takes a sample of her students to learn a new task. The scores (number of trials) are as follows: 5, 9, 10, 11, 15, 5, 5,9,10,11,15,5.. Compute the sample mean, sum of squares, variance and standard deviation as an estimate of her total class of students. Show your work.