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62 UNIT 1 Exploring One-Variable Data

For other statistical reasons, the mean and standard deviation will become the
preferred measures of center and variability for the distribution of a quantitative
variable in future sections. You’ll see why when we get there!
Graphing calculators and computer software will calculate summary statis-
tics for you. Using technology to perform calculations will allow you to focus on
choosing the right methods and interpreting your results.
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2. Tech Corner CALCULATING SUMMARY STATISTICS

TI-Nspire and other technology instructions are on the book’s website at bfwpub.com/tps7e.
You can use technology to calculate measures of center and variability for a distribution of quantitative data.
We’ll illustrate using data on the percent air in a sample of 14 bags of chips from previous examples.

1. Type the values into list L1.
2. Press STAT , arrow over to the CALC menu, and choose 1-Var Stats.
OS 2.55 or later: In the dialog box, press 2nd 1 (L1) and ENTER to specify L1 as the List. Leave
FreqList blank. Arrow down to Calculate and press ENTER .
Older OS: Press 2nd 1 (L1) and ENTER .
Press the down arrow to see the rest of the one-variable statistics.

NORMAL FLOAT AUTO REAL RADIAN MP NORMAL FLOAT AUTO REAL RADIAN MP

1-Var Stats 1-Var Stats
X=42.57142857 SX=10.18078345
ƩX=596 X=9.810448408
ƩX 2 =26720 n=14
SX =10.18078345 minX=19
X =9.810448408 Q1 =39
n=14 Med=45.5
minX=19 Q3=49
Q1 =39 maXX=59

Note: The TI-83/84 does not give the range or interquartile range ( IQR ) directly when you calculate
one-variable statistics. But the calculator provides the five-number summary , so you can calculate range =

max − min and IQR = Q 3 − Q .

1
Some statistical software uses slightly different rules for calculating quar-
caution
tiles. We used Minitab statistical software to calculate summary statistics for

the percent air in chips data. In the output, Minitab reports that Q 1 = 37.75

.

and Q 3 = 49.25 The TI-83/84 gives the first and third quartiles as Q 1 = 39

and Q 3 = 49 , which match the values we calculated in an earlier example.
Results from the various rules are usually close to each other, especially for
large data sets.
Descriptive Statistics
Variable N Mean StDev Minimum Q 1 Median Q 3 Maximum
Percent air 14 42.57 10.18 19.00 37.75 45.50 49.25 59.00

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