Your best estimate of the number of shoppers who enter your store and make a pur

Question

Your best estimate of the number of shoppers who enter your store and make a purchase is around 20%, but you want to do a study to accurately estimate it. You want to be able to estimate within a margin of error of 3% with 90% confidence.

5. What are the following: MoE, z, and /? (Whether you use or depends on whether you are calculating sample size for a mean or a proportion)

6. Based on your answers in question 5, calculate the minimum sample size needed.

7. If you want a smaller margin of error (e.g., 2%), will it increase or decrease the sample size?

8. Assume that you have no idea what the percentage will be for shoppers that make a purchase. What value should you assume the percentage is when calculating the minimum sample size?

You want to do a study to determine what percentage of UT students traveled into Mexico last month. You want your study to have 95% confidence with a margin of error of 5%, and you really have no idea what the percentage is.

9. What are the following: MoE, z, and /? (Whether you use or depends on whether you are calculating sample size for a mean or a proportion).

10. Based on your answers in question 9, calculate the minimum sample size needed.

Explanation / Answer

Your best estimate of the number of shoppers who enter your store and make a purchase is around 20%, but you want to do a study to accurately estimate it. You want to be able to estimate within a margin of error of 3% with 90% confidence.

5. What are the following: MoE, z, and /? (Whether you use or depends on whether you are calculating sample size for a mean or a proportion)

Q5.

MoE 0.03

z = 1.645

= 0.20

Q6.

Compute Sample Size ( n ) = n=(Z/E)^2*p*(1-p)

Z a/2 at 0.1 is = 1.645

Sample Proportion = 0.2

ME = 0.03

n = ( 1.645 / 0.03 )^2 * 0.2*0.8

= 481.0711 ~ 482

Q7.

it will increase the sample size

Q8.

we asuume 0.50 as percentage when no prior estimate is given

Q9.

Compute Sample Size ( n ) = n=(Z/E)^2*p*(1-p)

Z a/2 at 0.1 is = 1.645

Sample Proportion = 0.5

ME = 0.03

n = ( 1.645 / 0.03 )^2 * 0.5*0.5

= 751.6736 ~ 752

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