Quiz 4

What would suggest that a dataset is not normal?

• The ggplot layer geom_histogram is showing observations that are norrowly distributed about the
• The ggplot layer geom_jitter() is showing large number of outliers
• The median() is several magnitude smaller than the mean()
• The summary() function is showing the first quartile is smaller than the third quartile

If the age in the class is approximately normally distributed, and if the mean age of a student is 28 with a standard deviation of 4, what proportion of the student would be between 24 and 32?

• 0
• 68
• 75
• 95

The geom_boxplot layer from the ggplot2 R package will display a box that starts at

• the lowest value in the data
• the highest value in the data
• the first quartile
• the median

The geom_boxplot layer from the ggplot2 R package is derived from

• the mean
• the median
• the quartiles
• all or the above

The geom_boxplot layer from the ggplot2 R package is a

• visual presentation of quartiles
• numerical presentation of quartiles
• numerical computation of the standard deviation
• simple plot showing the mean, median and mode

In a normal distribution, what proportion of the observations are within two standard deviations of the mean?

• 50
• 95
• 68
• 99.7

Which of the following is true about the median statistic in R?

• It is affected by extremely large or small values, and should therefore be avoided.
• To find the median, R users need to enter multiple lines of code in order to figure out the val
• It is the value that occurs most often, and requires the use of loops.
• It can be computed very easily in R with the function median()

The geom_histogram and the geom_boxplot layer from the ggplot2 R package could

• help determine if a continuous variable is normal
• determine the relation between two variables
• not be used for continuous data
• create confusion when exploring a new data set

When the R sd() function outputs the value -2.5, you conclude that

• the mean is greater than the median
• the median is greater than the mean
• the dispersion in the data is low
• this question is misleading

The geom_histogram layer from the ggplot2 R package has large gaps between the bars.

• True
• False