Analyzing Data
Takes numerical values for a measured or counted quantity.
Quantitative Variable
Stack up bars to make 100%
Segmented bar graph
This acronym reminds you how to describe or compare a distribution with context.
S.O.C.S. or S.O.C.V.
Shape. Outlier. Center. Spread/Variability
Resistant to change.
Median
Cumulative Relative Frequency
Percentile
This display shows frequency (how many) or relative frequency (percent).
Bar graph
Takes a fixed set of possible values with gaps between them.
Discrete Variable
Qunderset(1) -1.5(IQR)
Qunderset(3) +1.5(IQR)
Outlier rule
Mean and standard deviation are greatly affected by outliers.
Nonresistant
Describes how many standard deviations a value falls from the mean of the distribution and in what direction.
z-score (standardized score)
Assign labels that place individuals into groups.
Categorical Variables
Segmented bar graphs are different.
Association (Knowing the value of one variable helps predict the other variable).
mean < median
Skewed left
min, Qunderset(1), med,Qunderset(2), max
Five-number summary
same shape, mu=0, sigma=1
Standardizing a distribution
Knowing the value of one variable helps predict the other variable.
Association
Takes any value in an interval on the number line. (decimals).
Continuous Variable
mean ~~ median
Roughly symmetric
The heights of students at our school typically vary by about 3.1 inches from the mean height.
Standard deviation
If a distribution is approximately normal, then approximately 68%, 95%, and 99.7% of the data will be within
+-1sigma, +-2sigma, +-3sigma
Empirical Rule
The vertical axis of a display does not start at 0.
Misleading graph
Segmented bar graph where the width of bars is proportional to group size.
Mosaic plot
Median, IQR,
Qunderset(1),
Qunderset(3)
Resistant measures
sigma^2
Variance
Used to find the x-value on a normal distribution given a specific area. When using technology enter these paramters:
(area, mu, sigma)
invnorm