# Calculating The Population Standard Deviation - HP -22S Owner's Manual

Scientific calculator.

Example: Calculating the Mean and Standard
Deviation. Production supervisor May Kitt wants to determine how
long a certain process takes. She randomly picks six people, observes
them as they carry 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.
Keys:
.1
CLEAR
I
{I}
15.5
12:+ I
9.25
[EJ
10
12:+ I
12.5
1 2:+
112
1 2:+ I
8.5
12:+ I
1 STAT I
{;;e,y} {;;e}
1 STAT I
{s} {s,,}
Display:
n= 1.13131313
n=6.13131313
;':=11.2917
s,,=2.58138
Description:
Clears the statistical
registers.
Enters the first time.
Enters the remaining
data.
Calculates the mean.
Calculates the standard
deviation.
Calculating the Population Standard Deviation
The standard deviations calculated by
{s,,}
and
{Sy}
are the sam-
ple standard deviations. They assume that the data is a samplipg of a
larger, complete set of data. If the data constitutes the entire popula-
tion of data, the
true population standard deviation
can be computed by
calculating the mean of the original data, adding the mean to the sta-
tistical data using
12:+ I,
and then calculating the standard deviation.
64
5: Statistical Calculations  