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Standard deviation of
Standard deviation of
the x-values."
the y-values if you en-
tered y-data."
y-value (]
Estimate of X for a
Correlation
given value of y.
coefficient.t
x-value (]
Estimate of y for a
Correlation
given value of x.
coefficient.t
()
Slope (m) of the calcu-
y-intercept (b) of the
lated line.
calculated line.
* The standard deviation is a measure of how dispersed the numbers are about the mean.
The HP-20S calculates the sample standard deviation, which assumes the data is a sam-
pling of a larger, complete set of data. If the data constitutes the entire population of data,
the true population, refer to page 55, "Calculating the Population Standard Deviation."
t The correlation coefficient is a number in the range —1 through +1 that measures how
closely the data fits the calculated line. A value of +1 indicates a perfect positive correla-
tion, and —1 indicates a perfect negative correlation. A value close to zero indicates the
curve is a poor fit.
Mean, Standard Deviation, and Summation
Statistics
You can calculate the mean, standard deviation, n, Zx,
and Zx? of x-data. For x,y-data, you can also calculate the
mean and standard deviation of the y-data and Zy, Zy?,
and Zxy.
Example: Calculating the Mean, Standard Deviation, and Root
Mean Square. A yacht captain wants to determine how long it takes
to change a sail. She randomly chooses six members of her crew, ob-
serves them as they carry out the sail change, and records the number
of minutes required: 4.5, 4, 2, 3.25, 3.5, 3.75.
54
5: Statistical Calculations
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