Question

1. Below is the exam data for a sample my undergrad stats class. The average score was 79 for each of the exams. Answer the following questions without doing any calculations.

Student ID	Exam1	Exam2	Exam3
1	79	70	82
2	79	90	83
3	79	72	79
4	79	98	79
5	79	94	81
6	79	65	77
7	79	91	76
8	79	70	82
9	79	73	77
10	79	67	77

1. What is the standard deviation for Exam 1? How do you know?
2. Which of the three exams has the highest standard deviation? How do you know?
3. Consider the following population dataset where y = depression score on a depression inventory.

Person ID	y = depression score
1	660
2	580
3	780
4	590
5	700

1. What is the unit-of- analysis for this dataset?
2. Calculate the mean depression score.
3. Calculate the range in depression score.
4. Calculate the standard deviation of depression score.
5. Interpret the standard deviation in a sentence (as illustrated in slides).

3) A researcher asked 37 respondents how they felt about the following statement: “When a musical artist says something that goes against your own beliefs, you should not buy that artist’s music.” They were given the following options:

1. Disagree
2. Neutral
3. Agree

Ten of the respondents chose option (1); 20 of the respondents chose option (2); and seven of the respondents chose option (3).

The researcher concludes that the range for the data is 2.   Do you agree or disagree with the researcher? If you agree, why do you agree? If you disagree, why do you disagree and what is the actual range?

Answer 1

1)

a) Ans: standard deviation = 0

Given the average score is 79.

For the exam 1 all the students got 79.

We can say that the standard deviation is 0 , because none of the values are away from the average.

b) And : exam 2

we can directly say that the exam 2 has highest standard deviation because there is more scatteredness between the values from the mean.

Where as the dispersion is also more (max-min = 98-65 = 33)