Deck 6: Presenting Data: Descriptive Statistics

Question 1

For each of the following variables in a study, list the one best measure of central tendency you can use to describe the data, and a graph to depict the distribution of values (pick any one if more than one can be used)?
a) SAT scores
b) race/ethnicity
c) number of hours studied in the past week
d) birth order
e) type of car owned

Answer 1

Question 2

Here are some data from a study. Put into words what the following statements tell us:
-For a class of 50 people, the mean exam grade was 78.5, the median was 80, and the mode was 83.

Answer 2

Because the mean is lower than the median, it suggests that there is a slight positive skew; that is, there are more scores at the lower end pulling the mean lower. The most common grade was 83 and half the students scored above 80 or half scored below 80.

Question 3

Here are some data from a study. Put into words what the following statements tell us:
-Another class of 50 also had a mean exam grade of 78.5. However, the standard deviation for that class was 8.5, compared to the first class which had a standard deviation of 2.5. What do these standard deviations tell us?

Answer 3

They tell us that there is a wider dispersion of scores in the second class compared with the first one, where the scores tend to cluster closer to the mean of 78.5.

Question 4

Define the following:
-Type I error:

Question 5

Define the following:
-Central Limit Theorem

Question 6

Define the following:
-the median:

Question 7

Define the following:
-valid percent:

Question 8

The mode is always the answer selected by the majority.

Question 9

If grades on the last Quantitative Methods exam were approximately normally distributed with a mean of 70 and a standard deviation of 10, what percentage of students received grades:
-less than 70? _______

Question 10

If grades on the last Quantitative Methods exam were approximately normally distributed with a mean of 70 and a standard deviation of 10, what percentage of students received grades:
-greater than 90? ______

Question 11

If grades on the last Quantitative Methods exam were approximately normally distributed with a mean of 70 and a standard deviation of 10, what percentage of students received grades:
-between 60 and 80? ______

Question 12

If grades on the last Quantitative Methods exam were approximately normally distributed with a mean of 70 and a standard deviation of 10, what percentage of students received grades:
-what is the mode on this exam? ______

Question 13

If grades on the last Quantitative Methods exam were approximately normally distributed with a mean of 70 and a standard deviation of 10, what percentage of students received grades:
-what is the median grade on this exam? ______

Question 14

There are 100 marbles in a bag: 60 red ones, 30 blue, and 10 yellow.
-what are the odds of selecting a red one?

Question 15

There are 100 marbles in a bag: 60 red ones, 30 blue, and 10 yellow.
-what is the probability of choosing a yellow one or a blue one?