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

Accepted Answer

$~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Statistic~~~~~~~~~~~~~~~~~~~~Graph/Chart\
\begin{array}{|l|l|l|}
\hline \text { a) SAT scores } & \text { mean } & \begin{array}{l}
\text { Histogram or } \
\text { frequency graph }
\end{array} \
\hline \text { b) race/ethnicity } & \text { mode } & \text { Bar or pie chart } \
\hline \text { c) number of hours studied in the past week } & \text { mean } & \text { Frequency graph } \
\hline \text { d) birth order } & \text { median } & \text { Bar or pie chart } \
\hline \text { e) type of car owned } & \text { mode } & \text { Bar or pie chart } \
\hline
\end{array}$

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.

Accepted Answer

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?

Accepted Answer

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:

Accepted Answer

The answer of Define the following:
-Type I error:...

Question 5

Define the following:
-Central Limit Theorem

Accepted Answer

The answer of Define the following:
-Central Limit Theorem...

Question 6

Define the following:
-the median:

Accepted Answer

The answer of Define the following:
-the median:...

Question 7

Define the following:
-valid percent:

Accepted Answer

The answer of Define the following:
-valid percent:...

Question 8

The mode is always the answer selected by the majority.

Accepted Answer

although the majority answer is always the mode, the mode is the most frequently selected answer which may not have been chosen by more than 50 percent.

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? _______

Accepted Answer