WGU C955 APPLIED PROBABILITY AND
STATISTICS FINAL PREPARATION
◉ The Empirical Rule. Answer: According to The Empirical Rule,
approximately 68% of the data points in a dataset will be within 1
standard deviation of the mean. 95% of all values are within 2
standard deviations of the mean.
◉ Normal distribution. Answer: In a normal distribution data is
symmetrical, so the mean, median, and mode are all equal.
◉ measure of spread. Answer: Measures of spread describe how
similar or varied the set of observed values are for a particular
variable (data item). Measures of spread include the range, quartiles
and the interquartile range, variance and standard deviation.
◉ Standard Deviation Rule 2 and 3 deviations. Answer: According
the the Standard Deviation Rule, approximately 2.35 percent of all
values will fall between 2 and 3 standard deviations above the mean.
◉ How are the mode and mean of a sample related if the
distribution is positively skewed?. Answer: The mode is less than the
mean.
,◉ A set of data is normally distributed with a mean of 85 and
standard deviation 20. The data point values that fall within one
standard deviation range from ___________ to ___________?. Answer: We
know that the standard deviation is 20. To obtain the values that are
one standard deviation above and below the mean, we do the
following: To obtain the first value, we will subtract 20 from the
mean: 85 −20 =65 To obtain the second value, we will add 20 to the
mean: 85 +20 =105 Therefore, the data values that will fall within 1
standard deviation of the mean will range from 65 to 105.
◉ best used to display categorical data. Answer:
◉ How are the mean, median, and mode of a sample related if the
distribution is normally distributed?. Answer: The values are all
equal
◉ IQR (interquartile range). Answer: Q3-Q1
◉ standard deviation. Answer: Using the Standard Deviation Rule,
we know that when data is normally distributed, 50% of the values
fall above the mean, and 50% of the values fall below the mean.
◉ population sample from a box plot.. Answer: It is not possible to
estimate the size of the population sample from a box plot.
, ◉ Pie chart. Answer: A pie chart is the best type of graph to use to
show categorical data, where each category represents a share of the
total as a percent.
◉ Scatterplot. Answer: A scatterplot is a graphical display that
shows the explanatory variable on the x-axis and the response
variable on the y-axis. Is useful when both variables in the data set
are quantitative.
◉ Cluster. Answer: If several points are grouped together away from
the majority of points, we call them a cluster.
◉ two-way frequency table.. Answer: The best method to display
two categorical (words) variables is a two-way frequency table.
Has rows and columns
◉ Side-by-side box plots. Answer: Side-by-side boxplots are useful
when the explanatory variable is categorical and the response
variable is quantitative.
◉ Simpson's Paradox. Answer: A counterintuitive situation in which
a trend in different groups of data disappears or reverses when the
groups are combined. Simpson's paradox is avoided by having an
STATISTICS FINAL PREPARATION
◉ The Empirical Rule. Answer: According to The Empirical Rule,
approximately 68% of the data points in a dataset will be within 1
standard deviation of the mean. 95% of all values are within 2
standard deviations of the mean.
◉ Normal distribution. Answer: In a normal distribution data is
symmetrical, so the mean, median, and mode are all equal.
◉ measure of spread. Answer: Measures of spread describe how
similar or varied the set of observed values are for a particular
variable (data item). Measures of spread include the range, quartiles
and the interquartile range, variance and standard deviation.
◉ Standard Deviation Rule 2 and 3 deviations. Answer: According
the the Standard Deviation Rule, approximately 2.35 percent of all
values will fall between 2 and 3 standard deviations above the mean.
◉ How are the mode and mean of a sample related if the
distribution is positively skewed?. Answer: The mode is less than the
mean.
,◉ A set of data is normally distributed with a mean of 85 and
standard deviation 20. The data point values that fall within one
standard deviation range from ___________ to ___________?. Answer: We
know that the standard deviation is 20. To obtain the values that are
one standard deviation above and below the mean, we do the
following: To obtain the first value, we will subtract 20 from the
mean: 85 −20 =65 To obtain the second value, we will add 20 to the
mean: 85 +20 =105 Therefore, the data values that will fall within 1
standard deviation of the mean will range from 65 to 105.
◉ best used to display categorical data. Answer:
◉ How are the mean, median, and mode of a sample related if the
distribution is normally distributed?. Answer: The values are all
equal
◉ IQR (interquartile range). Answer: Q3-Q1
◉ standard deviation. Answer: Using the Standard Deviation Rule,
we know that when data is normally distributed, 50% of the values
fall above the mean, and 50% of the values fall below the mean.
◉ population sample from a box plot.. Answer: It is not possible to
estimate the size of the population sample from a box plot.
, ◉ Pie chart. Answer: A pie chart is the best type of graph to use to
show categorical data, where each category represents a share of the
total as a percent.
◉ Scatterplot. Answer: A scatterplot is a graphical display that
shows the explanatory variable on the x-axis and the response
variable on the y-axis. Is useful when both variables in the data set
are quantitative.
◉ Cluster. Answer: If several points are grouped together away from
the majority of points, we call them a cluster.
◉ two-way frequency table.. Answer: The best method to display
two categorical (words) variables is a two-way frequency table.
Has rows and columns
◉ Side-by-side box plots. Answer: Side-by-side boxplots are useful
when the explanatory variable is categorical and the response
variable is quantitative.
◉ Simpson's Paradox. Answer: A counterintuitive situation in which
a trend in different groups of data disappears or reverses when the
groups are combined. Simpson's paradox is avoided by having an
