Sample Size Calculator for a Completion Rate

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There are 10 Comments

October 22, 2010 | James Terrell wrote:

Very Useful.
I would also like to have Confidence as an input rather than restrict it to 95%.
Also, an article on the math behind the tables would be entertaining 

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July 8, 2009 | Amir Raza wrote:

how we compute sample size for median(IQR) comparison between groups 

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June 24, 2009 | Ofori Boateng wrote:

I am about looking to determine my sample size of how many managers I should select to from six companies for my survey so that my sample size and frame will be valid. Unfortunately I do not have the total number of managers that are working for these phone companies in Ghana and it is becoming increasing difficult for me to find the numbers. Is there a way for me to determine this unknown sample size. The tpye of managers I need for my survey are those in operations research, financial operations, and makerting department. Please try and help me here.

Thank you.

Ofori Boateng 

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June 6, 2009 | Thomas Smith wrote:

) "Why is population shape of concern when estimating a mean? What does sample size have to do?" 

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June 6, 2009 | Thomas Smith wrote:

The mean of a data sample, size n, forms an approximately normal distribution. ... Sample size n is about 30 to be sure that the central limit theorem applies. 

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June 6, 2009 | Thomas Smith wrote:

In 1992, the FAA conducted 86,991 pre-employment drug tests on job applicants who were to be engaged in safety and security-related jobs, and found that 1,143 were positive. (a) Construct a 95 percent confidence interval for the population proportion of positive drug tests. (b) Why is the normality assumption not a problem, despite the very small value of p? 

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June 6, 2009 | Thomas Smith wrote:

A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were 3.087 3.131 3.241 3.241 3.270 3.353 3.400 3.411 3.437 3.477 (a) Construct a 90 percent confidence interval for the true mean weight. (b) What sample size would be necessary to estimate the true weight with an error of ± 0.03 grams with 90 percent confidence? (c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture. 

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April 16, 2009 | Brad Woodruff wrote:

What is the best way to calculate sample size for an incidence rate, such as a mortality rate? 

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February 10, 2009 | theresa wood wrote:

3. A researcher is interested in estimating the average salary of fire fighters in a large city. He wants to be 95% confident that his estimate is correct. If the standard deviation is $1050, how large a sample is needed to get the desired information and to be accurate within $200? 

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May 17, 2008 | Chris wrote:

How do you calculate a confidence interval when the population standard deviation is unknown? 

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