HP -32S Owner's Manual page 159

• PressMfSTATl {x,y} {xw} for the weighted mean of the x-values
using the y-values as weights or frequencies. The weights can be
integers or non-integers.
The Standard Deviation (s) Menu. Standard deviation is a measure
of how dispersed the data values are about the mean.
• Press IB stat I {s} {sx} for the standard deviation of the x-
values.*
• Press Hi stat I {s} {sy} for the standard deviation of the y-
values.*
Example: Mean and Standard Deviation With One Variable.
Production supervisor May Kitt wants to determine how long a cer
tain process takes. She randomly picks ten people, observes each one
as he or she carries out the process, and records the number of min
utes required:
15.5 9.25 10.0
12.5 12.0 8.5
Calculate the mean and standard deviation of the times. (Treat all
these data as x-values.)
Keys:
Display:
Description:
•1 CLEAR| <Zr
Clears the statistics
registers.
15.5 [2+1
1.0000
Enters the first time.
9.25 [2+1 10 [2+1
12.5 [2+] 12 [2+]
8.5 U+]
3.0000
5.0000
6.0000
11.2917
Enters the remaining
data.
•ISTATI \x,y\ \x\
Calculates mean.
'This calculates the sample standard deviation (using n—1 as a divisor), which assumes the
data is a samplingof a larger, completeset of data. If your data constitutethe entire popula
tion of data, the true population standard deviation can be computed by calculatingthe mean
of the originaldata, adding the mean to the statisticaldata usingI2+1,and then calculating
the standard deviation.
11: Statistical Operations 157