Confidence Intervals - Casio ClassPad 300 User Manual

7-10 Confidence Intervals

A confidence interval is a range of values that has a specified probability of containing the
parameter being estimated.
A confidence interval that is too broad makes it difficult to get an idea of where the parameter
(actual value) is located. A narrow confidence interval, on the other hand, limits the
parameter range and makes it possible to obtain highly accurate results.
The commonly used confidence levels are 68%, 95% and 99%. Raising the confidence level
broadens the confidence interval. Conversely, lowering the confidence level narrows the
confidence interval, but it also creates the risk that parameters will be missed. With a
confidence interval of 95%, for example, there is a 5% probability that a parameter will not be
within the interval.
The following is a list of confidence intervals and a description of what each obtains.
Confidence Interval Name
Z
1-Sample Interval
Z
2-Sample Interval
Z
1-Prop Interval
Z
2-Prop Interval
t
1-Sample Interval
t
2-Sample Interval
k General Confidence Interval Precautions
If you input a C-Level (confidence level) value in the range of 0 < C-Level < 1, the value you
input is used. To specify a C-Level of 95%, for example, input "0.95".
7-10-1
Confidence Intervals
Obtains the confidence interval for the population mean when the
population standard deviation is known.
Obtains the confidence interval for the difference between population
means when the population standard deviations of two populations are
known.
Obtains the confidence interval of the proportion of successes in a
population.
Obtains the confidence interval of the difference between the
proportions of successes of two populations.
Obtains the confidence interval for the population mean when the
population standard deviation is unknown.
Obtains the confidence interval for the difference between two
population means when the population standard deviations are
unknown.
20021201
Description