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1 A heart fills with loving kindness is a likeable person indeed.

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Presentation on theme: "1 A heart fills with loving kindness is a likeable person indeed."— Presentation transcript:

1 1 A heart fills with loving kindness is a likeable person indeed.

2 2 Estimating Proportions and Means Sample estimates Confidence intervals Approximate confidence intervals for p and 

3 3 Review Unit: a person or object to be measured Population: collection of units about which we want information Sample: collection of units we will measure Sample size: the number of units in a sample p: population proportion : sample proportion

4 4 Fundamental Rule for Using Data for Inference The available data can be used to make inferences about a much larger group if the data can be considered to be representative with regard to the questions of interest.

5 5 Estimation Sample estimate of a numerical summary of population (a parameter) is the same numerical summary of sample (a statistic) Eg.Sample estimate of population proportion p is sample proportion Margin of error for k%: the difference between sample estimate and the parameter is less than margin of error for k% about k% of time.

6 6 Estimation A k% confidence interval (C.I.) for a parameter is an interval of values computed from sample data that includes the parameter k% of time: Sample estimate + margin of error for k%

7 7 p

8 8 Approximate C.I. for p When are both at least 10: Margin of error for k% is about where z* is the z score from the standard normal probability table corresponding to (1/2+k/2%).

9 9 Approximate C.I. for p An approximate k% C.I. for p is An approximate 95% C.I. for p is

10 10 Approximate C.I. for  When 1. Either the population follows normal curve 2. Or the sample size n > 30 The margin of error for k% is about where t* is the t score from the t probability table corresponding to k% and (n-1) df.

11 11 Approximate C.I. for  An approximate k% C.I. for  is

12 12


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