Using Frequencies And Categories - Texas Instruments TI-89 Manual Book

Using Frequencies and Categories

Example of a
Frequency Column
Tip: A frequency value of 0
effectively removes the data
point from analysis.
Note: You can also use
frequency values from a list
variable instead of a
column.
Example of a
Category Column
270 Chapter 16: Statistics and Data Plots
To manipulate the way in which data points are analyzed, you
can use frequency values and/or category values. Frequency
values let you "weight" particular data points. Category values
let you analyze a subset of the data points.
In a data variable, you can use any column in the Data/Matrix Editor
to specify a frequency value (or weight) for the data points on each
row. A frequency value must be an integer ‚ 0 if
or or if
OneVar MedMed
calculations or plots, the frequency value can be any number ‚ 0.
For example, suppose you enter a student's test scores, where:
¦
The mid-semester exam is weighted twice as much as other tests.
¦
The final exam is weighted three times as much.
In the Data/Matrix Editor, you can enter the test scores and
frequency values in two columns.
Test scores
Frequency values
c1 c2
85 1
weighted scores
are equivalent to
97 1
the single column
92 2
of scores listed to
89 1
91 1
95 3
To use frequency values, specify the frequency column when you
perform a statistical calculation or define a stat plot. For example:
Set this to YES.
Type the column
number (or list
name) that
contains the
frequency values.
In a data variable, you can use any column to specify a category (or
subset) value for the data points on each row. A category value can
be any number.
. For other statistical
Plot Type = Box Plot
These c1
85
97
92
92
the right.
89
91
95
95
95
Calculation Type =
Frequency of 2
Frequency of 3