BUSINESS ANALYTICS FINAL EXAM
REVIEW WITH 100% CORRECT
ANSWERS
Histogram - ANS-a graph for a quantitative variable; we usually slice up all the possible values into bins
and then count the number of cases that fall in each bin
Relative frequency histograms - ANS-percentages of each bin in the histogram
Stem-and-leaf displays - ANS-are like histograms, but they also give the individual values
Quantitative Data Condition - ANS-Before making a histogram or stem-and-leaf display; the data must
be values of a quantitative variable whose units are known
When describing a distribution, attention should be paid to - ANS-its shape, center, spread
Shape - ANS-a distribution in terms of its modes, its symmetry, and whether it has any gaps or outlying
values
Modes - ANS-Peaks or humps seen in a histogram
Unimodal - ANS-A distribution whose histogram has one main peak
Bimodal - ANS-Two main peaks
Multimodal - ANS-three or more peaks
Uniform - ANS-A distribution whose histogram doesn't appear to have any mode and in which all the
bars are approximately the same height
Symmetric - ANS-the halves on either side of the center look, at least approximately, like mirror images
Tails - ANS-The thinner ends of a distribution
Skewed - ANS-If one tail stretches out farther than the other: skewed to side of where tail is
Judgment call - ANS-Characterizing the shape of a distribution
,The mean is a natural summary for - ANS-unimodal, symmetric distributions
Mean - ANS-sum of y values (or x values)/ number of variables
If a distribution is skewed, contains gaps, or contains outliers, then it is better to use - ANS-the median
The median is - ANS-resistant
Range - ANS-max-min; not resistant to unusual observations
quartiles - ANS-values that frame the middle 50% of the data. One quarter of the data lies below the
lower quartile, Q1, and one quarter lies above the upper quartile, Q3
The interquartile range (IQR) - ANS-defined to be the difference between the two quartile values; Q3-Q1
Standard deviation - ANS-takes into account how far each value is from the mean; appropriate for
symmetric distributions; square root of the variance
Variance - ANS-(s^2) average of the squared deviations; sum of (y value minus the mean)^2 / n-1
If the shape is skewed - ANS-the median and IQR should be reported
If the shape is unimodal and symmetric - ANS-the mean and standard deviation and possibly the median
and IQR should be reported
Always pair the median with - ANS-IQR
Always pair the mean with - ANS-standard deviation
Z-score - ANS-the standardized value tells how many standard deviations each value is above or below
the overall mean; x minus the mean/ standard deviation
The five-number summary of a distribution - ANS-reports its median, quartiles, and extremes (maximum
and minimum)
Boxplot - ANS-highlights several features of the distribution of the variable, including the quartiles, the
median, and any outlying values
Time series plot - ANS-A display of values against time
Smooth trace - ANS-To better understanding the trend of times series data
Stationary - ANS-when a time series is without a strong trend or change in variability
Scatterplot - ANS-plots one quantitative variable against another, is an effective display to look for
trends, patterns, and relationships between two quantitative variables
, Negative pattern - ANS-A pattern that runs from the upper left to the lower right
Positive pattern - ANS-A pattern running from the lower left to the upper right
Linear - ANS-If there is a straight-line relationship, it will appear as a cloud or swarm of points stretched
out in a generally consistent, straight form
Form - ANS-straight, curved, exotic
Strength - ANS-how much scatter or cluster
Outlier - ANS-unusual observation, standing away from the overall pattern of the scatterplot
We place the explanatory or predictor variable on - ANS-the x-axis
We place the response variable on - ANS-the y-axis
The x- and y-variables are sometimes referred to as - ANS-the independent and dependent variables
x variable - ANS-independant
y variable - ANS-dependant
Correlation coefficient - ANS-Since x's and y's are paired, multiply each standardized value of x by the
standardized value it is paired with and add up those cross products. Divide by n -1.The ratio of the sum
of the product zxzy for every point in the scatterplot to n - 1
Correlation - ANS-measures the strength of the linear association between two quantitative variables
Before using correlation, you must check - ANS-Quantitative Variable Condition
Linearity Condition
Outlier Condition
Quantitative Variables Condition - ANS-Correlation applies only to quantitative variables
Linearity Condition - ANS-Correlation measures the strength only of the linear association. If the
underlying relationship is curved, summarizing its strength with a correlation would be misleading.
Outlier Condition - ANS-Unusual observations can distort the correlation. When you see an outlier, it's
often a good idea to report the correlation both with and without the point.
Correlation is always between - ANS--1 and +1
Correlation treats x and y - ANS-symmetrically
Correlation is not affected by changes in - ANS-the center or scale of either variable
Correlation measures - ANS-the strength of the linear association between the two variables.
REVIEW WITH 100% CORRECT
ANSWERS
Histogram - ANS-a graph for a quantitative variable; we usually slice up all the possible values into bins
and then count the number of cases that fall in each bin
Relative frequency histograms - ANS-percentages of each bin in the histogram
Stem-and-leaf displays - ANS-are like histograms, but they also give the individual values
Quantitative Data Condition - ANS-Before making a histogram or stem-and-leaf display; the data must
be values of a quantitative variable whose units are known
When describing a distribution, attention should be paid to - ANS-its shape, center, spread
Shape - ANS-a distribution in terms of its modes, its symmetry, and whether it has any gaps or outlying
values
Modes - ANS-Peaks or humps seen in a histogram
Unimodal - ANS-A distribution whose histogram has one main peak
Bimodal - ANS-Two main peaks
Multimodal - ANS-three or more peaks
Uniform - ANS-A distribution whose histogram doesn't appear to have any mode and in which all the
bars are approximately the same height
Symmetric - ANS-the halves on either side of the center look, at least approximately, like mirror images
Tails - ANS-The thinner ends of a distribution
Skewed - ANS-If one tail stretches out farther than the other: skewed to side of where tail is
Judgment call - ANS-Characterizing the shape of a distribution
,The mean is a natural summary for - ANS-unimodal, symmetric distributions
Mean - ANS-sum of y values (or x values)/ number of variables
If a distribution is skewed, contains gaps, or contains outliers, then it is better to use - ANS-the median
The median is - ANS-resistant
Range - ANS-max-min; not resistant to unusual observations
quartiles - ANS-values that frame the middle 50% of the data. One quarter of the data lies below the
lower quartile, Q1, and one quarter lies above the upper quartile, Q3
The interquartile range (IQR) - ANS-defined to be the difference between the two quartile values; Q3-Q1
Standard deviation - ANS-takes into account how far each value is from the mean; appropriate for
symmetric distributions; square root of the variance
Variance - ANS-(s^2) average of the squared deviations; sum of (y value minus the mean)^2 / n-1
If the shape is skewed - ANS-the median and IQR should be reported
If the shape is unimodal and symmetric - ANS-the mean and standard deviation and possibly the median
and IQR should be reported
Always pair the median with - ANS-IQR
Always pair the mean with - ANS-standard deviation
Z-score - ANS-the standardized value tells how many standard deviations each value is above or below
the overall mean; x minus the mean/ standard deviation
The five-number summary of a distribution - ANS-reports its median, quartiles, and extremes (maximum
and minimum)
Boxplot - ANS-highlights several features of the distribution of the variable, including the quartiles, the
median, and any outlying values
Time series plot - ANS-A display of values against time
Smooth trace - ANS-To better understanding the trend of times series data
Stationary - ANS-when a time series is without a strong trend or change in variability
Scatterplot - ANS-plots one quantitative variable against another, is an effective display to look for
trends, patterns, and relationships between two quantitative variables
, Negative pattern - ANS-A pattern that runs from the upper left to the lower right
Positive pattern - ANS-A pattern running from the lower left to the upper right
Linear - ANS-If there is a straight-line relationship, it will appear as a cloud or swarm of points stretched
out in a generally consistent, straight form
Form - ANS-straight, curved, exotic
Strength - ANS-how much scatter or cluster
Outlier - ANS-unusual observation, standing away from the overall pattern of the scatterplot
We place the explanatory or predictor variable on - ANS-the x-axis
We place the response variable on - ANS-the y-axis
The x- and y-variables are sometimes referred to as - ANS-the independent and dependent variables
x variable - ANS-independant
y variable - ANS-dependant
Correlation coefficient - ANS-Since x's and y's are paired, multiply each standardized value of x by the
standardized value it is paired with and add up those cross products. Divide by n -1.The ratio of the sum
of the product zxzy for every point in the scatterplot to n - 1
Correlation - ANS-measures the strength of the linear association between two quantitative variables
Before using correlation, you must check - ANS-Quantitative Variable Condition
Linearity Condition
Outlier Condition
Quantitative Variables Condition - ANS-Correlation applies only to quantitative variables
Linearity Condition - ANS-Correlation measures the strength only of the linear association. If the
underlying relationship is curved, summarizing its strength with a correlation would be misleading.
Outlier Condition - ANS-Unusual observations can distort the correlation. When you see an outlier, it's
often a good idea to report the correlation both with and without the point.
Correlation is always between - ANS--1 and +1
Correlation treats x and y - ANS-symmetrically
Correlation is not affected by changes in - ANS-the center or scale of either variable
Correlation measures - ANS-the strength of the linear association between the two variables.
