HP 33s - Manual (Page 150)

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 { σº} 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 | { σº} for the population standard deviation of the x–values.
„ Press | { σ¸} for the population standard deviation of the y–values.