Free Practice Quiz Question List

4 Descriptive Statistics Online Quiz Questions

Use this free practice quiz with 20 questions to review 4 Descriptive Statistics, test your knowledge, and prepare for your next test or exam.

20 questions

True or false

1 point

A numerical summary of observed data, by itself, establishes that the same pattern holds in a broader population.

A
True
B
False

Fill in the blank

1 point

A z-score of $-1$ means that a value is standard deviation below the mean.

Choose one

1 point

A quantitative distribution is strongly skewed because of one unusually large observation. Which measure is generally less affected by that observation when describing the distribution's center?

A
The mean, because it uses every observation
B
The median, because it is less affected by extreme values
C
The mode, because it is always the middle value
D
The range, because it measures the center

Written response

1 point

For the data $3, 5, 8, 12$ , what is the arithmetic mean?

Choose all

1 point

Select all statements that correctly describe the correlation coefficient $r$ for two quantitative variables.

A
The sign of $r$ indicates the direction of the linear association.
B
A positive value of $r$ proves that one variable causes the other to increase.
C
The correlation coefficient summarizes the strength of a linear association.
D
The correlation coefficient necessarily captures any curved relationship.

Fill in the blank

1 point

Complete the formula: the interquartile range (IQR) is .

True or false

1 point

Calculating the arithmetic mean of color labels is a meaningful way to summarize their center.

A
True
B
False

Choose one

1 point

A researcher wants to compare a quantitative measurement across several categorical groups. Which display is especially useful for comparing group medians, spread, and possible outliers?

A
A scatterplot of the category labels against the quantitative values
B
A histogram that combines all groups without distinguishing them
C
Side-by-side box plots, one for each category
D
A pie chart of the quantitative values

Written response

1 point

What statistic, denoted by $r$ , summarizes the direction and strength of a linear association between two quantitative variables?

Choose all

1 point

A distribution is skewed and contains an influential outlier. Select the two measures that are best paired to describe its center and spread.

A
Median
B
Mean
C
Interquartile range
D
Standard deviation

Choose one

1 point

Which statement best describes the interpretation of the $p$ th percentile in a dataset?

A
The $p$ th percentile is always exactly $p$ observations above every other value.
B
The $p$ th percentile is approximately at or above about $p\%$ of observations, depending on the calculation convention.
C
The $p$ th percentile is the mean of the largest $p$ observations.
D
The $p$ th percentile is necessarily the most frequent value.

Open ended

1 point

Two groups have the same count of people with a particular response, but the groups are different sizes. Explain why comparing the counts alone may be misleading and what information should be reported to compare the groups responsibly.

Choose one

1 point

For a sample of size $n$ , what denominator is used in the usual sample variance when calculating the average squared deviation from the sample mean?

A
$n$
B
$n-1$
C
$N+1$
D
The number of distinct values

True or false

1 point

If a measurement is recorded in metres, its standard deviation is also expressed in metres.

A
True
B
False

Choose one

1 point

A researcher wants to compare the distribution of test scores across four teaching groups. Which display is most suitable for comparing group medians, spread, and possible outliers?

A
A scatterplot of the group labels against the quantitative values
B
Side-by-side box plots of the quantitative values for each group
C
A histogram that combines all groups into one distribution
D
A table showing only the overall mean

Choose one

1 point

A distribution of household incomes is strongly right-skewed and includes a few unusually high values. Which pair of summaries is generally most appropriate for describing its center and spread?

A
Mean and standard deviation
B
Mean and range
C
Median and IQR
D
Mode and variance

Written response

1 point

A z-score describes a value's distance from the mean in what units?

Choose one

1 point

For the sample data $2, 4, 6$ , what is the usual sample variance?

A
$2$
B
$4$
C
$\frac{8}{3}$
D
$8$

Written response

1 point

Find the range of the data set $12, 18, 21, 25, 30$ .

Choose one

1 point

A data set records lengths in centimeters. In which units is its standard deviation expressed?

A
Centimeters
B
Square centimeters
C
No units
D
Standard-deviation units