STT 215 TEST 1 QUESTIONS AND ANSWERS
1. Explain why distributions of categorical variables do not have a shape. -
ANSWER The values of a categorical variable can be put in any order, each
leading to different shapes, so there is no unique shape.
2. Under what circumstances is it better to use a histogram than a stemplot? -
ANSWER A histogram is better than a stemplot for extremely large data sets,
and when you need more control over the interval widths (bins). (For a stemplot
where leaves are 10s, your only choice of interval widths are 10, 5, 2, and 1.)
3. Under what circumstances is it better to use the mean than the median? -
ANSWER The mean is better than the median when there are no outliers in the
data set and the distribution is roughly symmetric (or not skewed).
Explain what it means for two events to be independent of each other -
ANSWER If knowing the out come of one event will not change the
probability of another event from occurring.
How do you drecrease the margin of error? - ANSWER Increase the sample
size
Explain the sampling distribution of a statistic - ANSWER distribution of
numbers you get if you take every possible sample of size (n) from the
population and evaluate the statistic for each one.
Explain the Area Principle - ANSWER the area
occupied by a part of the graph should correspond to the
magnitude of the value it represents.
Under what conditions do you use the mean and standard deviation to measure
the center and spread of a data set? - ANSWER When there are no outliers and
when the data set is symmetric.
Explain the difference between a discrete and a continuous random variable. -
ANSWER A Discrete random variable is a finite or countably infinite number
1. Explain why distributions of categorical variables do not have a shape. -
ANSWER The values of a categorical variable can be put in any order, each
leading to different shapes, so there is no unique shape.
2. Under what circumstances is it better to use a histogram than a stemplot? -
ANSWER A histogram is better than a stemplot for extremely large data sets,
and when you need more control over the interval widths (bins). (For a stemplot
where leaves are 10s, your only choice of interval widths are 10, 5, 2, and 1.)
3. Under what circumstances is it better to use the mean than the median? -
ANSWER The mean is better than the median when there are no outliers in the
data set and the distribution is roughly symmetric (or not skewed).
Explain what it means for two events to be independent of each other -
ANSWER If knowing the out come of one event will not change the
probability of another event from occurring.
How do you drecrease the margin of error? - ANSWER Increase the sample
size
Explain the sampling distribution of a statistic - ANSWER distribution of
numbers you get if you take every possible sample of size (n) from the
population and evaluate the statistic for each one.
Explain the Area Principle - ANSWER the area
occupied by a part of the graph should correspond to the
magnitude of the value it represents.
Under what conditions do you use the mean and standard deviation to measure
the center and spread of a data set? - ANSWER When there are no outliers and
when the data set is symmetric.
Explain the difference between a discrete and a continuous random variable. -
ANSWER A Discrete random variable is a finite or countably infinite number
