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Confidence Intervals

Confidence Interval Command List

kZ Confidence Interval

1-Sample Z Interval

Menu: ������������[Interval]-[One����-������Sample �����ZInt]

Description: This command obtains the confidence interval for the population mean when the population standard deviation is known.

The confidence interval is obtained using the following expressions.

Left = o – Z

 

α

σ

 

 

 

 

 

 

 

2

 

n

 

Right = o + Z

α

 

σ

2

 

 

 

 

 

n

α is the significance level, and 100 (1 – α)% is the confidence level. When the confidence level is 95%, for example, you would input 0.95, which produces α = 1 – 0.95 = 0.05.

Definition of Terms

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

σ : population standard deviation (σ > 0)

List : list where sample data is located

Freq : frequency of sample (1 or list name)

o : sample mean

n : sample size (positive integer)

Calculation Result Output

Left : interval lower limit (left edge)

Right : interval upper limit (right edge)

o : sample mean

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

n : sample size

Example 1 (calculation with list)

list1 : { 299.4, 297.7, 301, 298.9, 300.2, 297 }

Population standard deviation : 3

Significance level : 5% ( = confidence level : 95%)

•Statistics Wizard Operation

(1)Input the data into [list1] in the Stat Editor.

(2)On the menu bar, tap [Calc] and then [Interval].

(3)Select [One-Sample ZInt] and [List], and then tap [Next >>].

(4)Input values.

(5)Select List [list1] and Freq [1].

(6)Tap [Next >>].

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