You want to obtain a sample to estimate a population proportion. Based on previous evidence, you believe the population proportion is approximately 70%. You would like to be 95% confident that your estimate is within 3% of the true population proportion. How large of a sample size is required?
Contingency Table
A contingency table can be defined as the visual representation of the relationship between two or more categorical variables that can be evaluated and registered. It is a categorical version of the scatterplot, which is used to investigate the linear relationship between two variables. A contingency table is indeed a type of frequency distribution table that displays two variables at the same time.
Binomial Distribution
Binomial is an algebraic expression of the sum or the difference of two terms. Before knowing about binomial distribution, we must know about the binomial theorem.
You want to obtain a sample to estimate a population proportion. Based on previous evidence, you believe the population proportion is approximately 70%. You would like to be 95% confident that your estimate is within 3% of the true population proportion. How large of a
Obtain the sample size of a preliminary estimate for p with 0.70.
The formula of sample size is,
Use EXCEL Procedure for finding the critical value of z.
Follow the instruction to obtain the critical value of z:
- Open EXCEL
- Go to Formula bar.
- In formula bar enter the function as“=NORMINV”
- Enter the probability as 0.975.
- Enter the mean as 0 and the Standard deviation as 1.
- Click enter
EXCEL output:
From the EXCEL output, the critical value of z at the 95% confidence level is 1.96.
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