11–6 Statistical Operations
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
|
{
Uº
} for the standard deviation of x–values.
Press
|
{
U¸
} for the standard deviation of y–values.
The {
σ
º
} 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:
{c
{
´
}
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.
|
{
Uº
}
UºU¸σºσ¸
)
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
|
{
σ
º
} for the population standard deviation of the x–values.
Press
|
{
σ
¸
} for the population standard deviation of the y–values.
