7-10-7

Confidence Intervals

Example

Data1 : 49, sample size : 61

Data2 : 38, sample size : 62

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

•Statistics Wizard Operation

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

(2)Select [Two-Prop ZInt] and then tap [Next >>].

(3)Input values.

(4)Tap [Next >>].

uProgram, eActivity or Main Application

Command: TwoPropZInt

Command Syntax

C-Level value, x1 value, n1 value, x2 value, n2 value

Input Example:

TwoPropZInt 0.95,49,61,38,62

kt Confidence Interval

1-Sample t Interval

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

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

The confidence interval is obtained using the following expressions. The confidence level is 100 (1 – α)%.

Left = o– tn – 1

α

xσn–1

2

 

 

n

 

Right = o+tn – 1

 

α

 

xσn–1

 

2

 

 

n

 

Definition of Terms

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

List : list where sample data is located

Freq : frequency of sample (1 or list name)

o : sample mean

xσn−1 : sample standard deviation (xσn−1 >0)

n : sample size (positive integer)

20070301