20 Questions About Statistics

MAT201

Introduction to Statistics

What is statistics?

Describe the differences between inferential statistics and descriptive statistics.

The call center received 30 phone calls on a Monday, below is the number of minutes each call lasted.

5 8 6 25 4 21 10 1 24 12

9 2 12 28 14 17 12 1 16 18

6 6 12 10 20 9 6 8 6

Make a frequency table for the data using five classes. Show class limits and frequencies.

Make a histogram and polygon of the data from question 3.

Use this data for Questions 5-9

Cost ($10K)	Development Time (Months)
59	64
54	60
59	63
58	72
71	78
55	69
55	69
54	67

What is the mean for costs?

What is the range for development time?

What is the variance for development time?

What is the median for cost?

Convert the following cost scores into z scores.

Costs ($10K)	Z scores Cost
59
54
59
58
71
55
55
54

The scores of one student on two different IQ tests are as follows:

IQ Test A IQ Test B

X=140 X=120

Mean=105 Mean=100

S=20 S=10

ZA = ZB =

Which test did the student do better on test A or test B?

Using the Z table and the answer from test A on question 10 above what percentage of students did the student do better than? (Find the area under the curve to solve.)

If a z score is 1.23, what is the area under the curve?

What does a correlation coefficient measure? Please include information on strength and direction in you answer.

Use the following table to calculate the correlation coefficient (r).

and Interpret the results in words.

Cost ($10K)	Development Time (Months)
59	54
54	68
59	69
58	71
71	78
55	59
55	69
54	67

A pharmaceutical company wants to know which drug treatment is best for people who suffer from anxiety. Participants are assigned to three different treatment groups (A, B &C) and asked to complete the Liebowitz Social Anxiety Scale. Below are the results for each treatment group after the treatment was administered.

Group A	Group B	Group C
62	42	80
81	52	57
75	31	87
58	80	64
67	22	28
48	71	29
26	68	62
36	76	45
25	23	18
42	31

a. State the null and research hypothesis

b. Set the level of risk

c. Select the appropriate test

d. Compute the obtained value.

e. Find the critical value

f. Compare the obtained value and the critical value.

g. State your decision.

h. Write the result

What is Type I error

When do you use a Cohen’s d score?

When do you use a Post Hoc test?

The average annual expenditure for health care by men is $1,096 with a standard deviation of $205 and women is $1,234 with a standard deviation of $310. A random sample of 10 men and 10 women were selected. Test to see if the mean expenditure for men is different then the mean expenditure for women.