STAT 211 EXAM PRACTICE QUESTIONS
AND 100% CORRECT ANSWERS!!
What is the definition of variation?
Difference in data values for each element of the population
What is the sample mean used to estimate?
Population mean
What is the median?
The 50th percentile of data
What is the mode?
The most frequent value in a data set
Define symmetrical distribution.
Distribution where left and right sides are mirror images
What is a left-skewed distribution?
Distribution with longer left tail than right tail
What is a right-skewed distribution?
Distribution with longer right tail than left tail
What does standard deviation measure?
Overall variation within a data set
IQR (interquartile range)
Q3-Q1, the middle 50% of the data
Upper - low
bin width
, The width of an interval that is used in making a histogram.
end point - starting / (num bins)
Histograms are used for
Showing quantitative data organised into classes (e.g. ages of people in years; 0-9, 10 -19, 20 -
29)
Bar graphs are used for
categorical data, number of bars are not your choice
Percentiles
Divide the data set into 100 equal parts. An observation at the Pth percentile is higher tha P
percent of all observations.
Quartiles
Values that divide a data set into four equal parts
Finding outliers from IQR
Val < Q1 - 3/2(IQR)
Val > Q3 +3/2(IQR)
What information can you get from box plot
min, max, iqr, q1, q3, median
Measures of center
mean, median, mode & outliers;
outliers have a strong effect on the
mean, but not median
Benefits of box plots
AND 100% CORRECT ANSWERS!!
What is the definition of variation?
Difference in data values for each element of the population
What is the sample mean used to estimate?
Population mean
What is the median?
The 50th percentile of data
What is the mode?
The most frequent value in a data set
Define symmetrical distribution.
Distribution where left and right sides are mirror images
What is a left-skewed distribution?
Distribution with longer left tail than right tail
What is a right-skewed distribution?
Distribution with longer right tail than left tail
What does standard deviation measure?
Overall variation within a data set
IQR (interquartile range)
Q3-Q1, the middle 50% of the data
Upper - low
bin width
, The width of an interval that is used in making a histogram.
end point - starting / (num bins)
Histograms are used for
Showing quantitative data organised into classes (e.g. ages of people in years; 0-9, 10 -19, 20 -
29)
Bar graphs are used for
categorical data, number of bars are not your choice
Percentiles
Divide the data set into 100 equal parts. An observation at the Pth percentile is higher tha P
percent of all observations.
Quartiles
Values that divide a data set into four equal parts
Finding outliers from IQR
Val < Q1 - 3/2(IQR)
Val > Q3 +3/2(IQR)
What information can you get from box plot
min, max, iqr, q1, q3, median
Measures of center
mean, median, mode & outliers;
outliers have a strong effect on the
mean, but not median
Benefits of box plots
