Unit ! Flashcards
objects described by a set of data.
Individual
any characteristic of an individual.
Variable
these variables place individuals into one of several groups or categories
Categorical Variables
these variables are numerical values for which It makes sense to find an average. ex Area Codes
Building floor numbers
quantitative variable
To display the distribution of categorical data, make a
bar graph
this gives the
percent or proportion of
individuals that have a specific value for one categorical variable.
marginal relative
frequency
gives the
percent or proportion of
individuals that have a
specific value for one
categorical variable and
a specific value for
another categorical
variable.
joint relative
frequency
gives the
percent or proportion of
individuals that have a
specific value for one
categorical variable
among individuals who
share the same value of
another categorical
variable (the condition).
conditional relative
frequency
The bars are
grouped together based
on the values of one of
the categorical variables
and placed side by side.
side by side bar graph
displays the distribution
of a categorical variable
as segments of a
rectangle, with the area
of each segment
proportional to the
percent of individuals in
the corresponding
category.
segmented bar graph
There is an __
between two variables if
knowing the value of
one variable helps us
predict the value of the
other.
association
If knowing the value of
one variable does not
help us predict the value
of the other, then there
is
no association
A —- shows each
data value as a dot
above its location on a
number line.
dotplot
A distribution is roughly symmetric if
if the right
side of the graph is
approximately a mirror image of the left side.
A distribution is skewed to the right if
the right side of the graph is much longer than the left.
A distribution is skewed to the left if
the left side of the graph is much longer than the right.
You can describe the distribution of a graph by
center, shape, outlier, and variability.
To describe shape?
Whether the distribution is symmetrical, skewed to the right, or skewed to the left.
Always be sure to include — when you are asked to describe a distribution. This means using the variable name, not just the units the variable is measured in.
CONTEXT
When comparing distributions of quantitative data, it’s not enough just to list values for the center and variability of each distribution. You must explicitly compare these values, using words like
greater than, less than, about the same as.
What two components does one need to have a proper description of a distribution?
Context, Comparative language
A — shows each
data value separated into
two parts: a stem, which
consists of all but the final
digit, and a leaf, the final
digit.
stemplot
Sometimes, We can get a better picture of the distribution in a stemplot by
splitting stems.
use this when Two distributions of the same quantitative variable can be compared
back-to-back stemplot
A —- shows each
interval of values as a bar. The
heights of the bars show the
frequencies or relative
frequencies of values in each
interval.
histogram
