HP 33S, User Manual

Page: 150 / 388

11–6
Statistical Operations
File name 33s-English-Manual-040130-Publication(Edition 2).doc Page : 388
Printed Date : 2004/1/30 Size : 13.7 x 21.2 cm
Sample Standard Deviation
Sample standard deviation is a measure of how dispersed the data values are
about the mean sample standard deviation assumes the data is a sampling of a
larger, complete set of data, and is calculated using
n – 1 as a divisor.
Press
º +
{

} for the standard deviation of x –values.
Press
º +
{  } for the standard deviation of y –values.
The {
σ

} and {
σ

} keys in this menu are described in the next section, "Population
Standard Deviation."
Example: Sample Standard Deviation.
Using the same process–times as in the above "mean" example, May Kitt now
wants to determine the standard deviation time (s
x
) of the process:
15.5
9.25
10.0
12.5 12.0 8.5
Calculate the standard deviation of the times. (Treat all the data as x –values.)
Keys: Display: Description:
¹ ¡
{  }  Clears the statistics registers.
15.5
/

Enters the first time.
9.25
/
10
/
12.5
/
12
/
8.5
/


Enters the remaining data; six
data points entered.
º +
{

}

σ

σ


Calculates the standard
deviation time.
Population Standard Deviation
Population standard deviation is a measure of how dispersed the data values are
about the mean. Population standard deviation assumes the data constitutes the
complete set of data, and is calculated using n as a divisor.
Press
º +
{
σ

} for the population standard deviation of the x –values.
Press
º +
{
σ

} for the population standard deviation of the y –values.