7-10-3

Confidence Intervals

Calculation Result Output

Left : interval lower limit (left edge)

Right : interval upper limit (right edge)

o : mean of sample data

xσ n–1 : sample standard deviation (Displayed only for list format.)

n : sample size

2-Sample Z Interval

Command: TwoSampleZInt￿

Description: This command obtains the confidence interval for the difference between population means when the population standard deviations of two populations are known.

The confidence interval is obtained using the following expressions.

The confidence level is 100 (1 – α)%.

Left = (o1

– o2)

– Z

α

 

 

σ 2

+

 

σ 2

 

 

 

 

 

 

1

 

 

 

2

 

 

 

2

 

 

 

n1

 

n2

 

 

 

 

 

 

 

 

 

Right = (o1 – o2) + Z

α

 

 

 

 

σ 2

+

σ 2

 

 

 

 

 

 

 

 

1

 

2

 

2

 

 

 

 

n1

 

n2

 

o1 : mean of sample 1 data

o2 : mean of sample 2 data

σ1 : population standard deviation of sample 1

σ2 : population standard deviation of sample 2

n1 : size of sample 1

n2 : size of sample 2

Command Syntax

Syntax 1 (list format)

C-Level value, σ 1 value, σ 2 value, List(1), List(2), Freq(1) (or 1), Freq(2) (or 1) * “Freq” can be omitted. Doing so sets “1” for “Freq”.

Syntax 2 (parameter format)

C-Level value, σ 1 value, σ 2 value, o1 value, n1 value, o2 value, n2 value

Definition of Terms

C-Level : confidence level (0 <C-Level < 1)

σ1 : population standard deviation of sample 1 (σ1 > 0)

σ2 : population standard deviation of sample 2 (σ2 > 0) List(1) : list where sample 1 data is located

List(2) : list where sample 2 data is located

Freq(1) : frequency of sample 1 (1 or list name)

Freq(2) : frequency of sample 2 (1 or list name)

o1 : mean of sample 1 data

n1 : size of sample 1 (positive integer)

o2 : mean of sample 2 data

n2 : size of sample 2 (positive integer)

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