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StatTutor Lesson - Choosing the Sample Size

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      Question 1

      57

      Question 1.

      In practice, do we ever use the theoretical margin of error?

      		A.
      		B.
      Incorrect. Since the theoretical margin of error requires us to know the value of p in order to estimate p, we do not use the theoretical margin of error.
      Correct. Since the theoretical margin of error requires us to know the value of p in order to estimate p, we do not use the theoretical margin of error.
      Incorrect. Try again.
      2

      Question 2

      85

      Question 2.

      What is a problem with the formula n=(z∗ME)2p∗(1−p∗) for finding sample size?

      		A.
      		B.
      		C.
      Incorrect. The researcher can set a desired margin of error and level of confidence, but needing a value for p* is problematic.
      Correct. The researcher can set a desired margin of error and level of confidence, but needing a value for p* is problematic.
      Incorrect. Try again.
      2

      Question 3

      165

      Question 3.

      When no value is available for p*, what value should be used?

      		A.
      		B.
      		C.
      Incorrect. When no value is available, use p* = 0.50 as it will produce an adequate sample size.
      Correct. When no value is available, use p* = 0.50 as it will produce an adequate sample size.
      Incorrect. Try again.
      2

      Question 4

      220

      Question 4.

      True or false: Larger populations require larger sample sizes than smaller populations to achieve the same margin of error.

      		A.
      		B.
      Incorrect. Population size is not part of the sample size formula.
      Correct. Population size is not part of the sample size formula.
      Incorrect. Try again.
      2

      Question 5

      257

      Question 5.

      With no prior information for the value of p*, what should we use?

      		A.
      		B.
      		C.
      Incorrect. Use p* = 0.50 when no prior information is available.
      Correct. Use p* = 0.50 when no prior information is available.
      Incorrect. Try again.
      2

      Question 6

      278

      Question 6.

      In a previous slide we learned that the sample size for estimating proportion with a 3% margin of error is between 1,000 and 1,100. Does sample size computed in this example met this requirement?

      		A.
      		B.
      Incorrect. 1,068 is between 1,000 and 1,100, so yes 1,068 mets this requirement.
      Correct. 1,068 is between 1,000 and 1,100, so yes 1,068 mets this requirement.
      Incorrect. Try again.
      2

      Applet

      308