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What sample size is needed to give a margin of error of 5\% with a 95\% confidence interval?

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What sample size is needed to give a margin of error of 5\% with a 95\% confidence interval?

For a 95 percent level of confidence, the sample size would be about 1,000.

What sample size is needed for a 95 confidence interval?

Remember that z for a 95\% confidence level is 1.96. Refer to the table provided in the confidence level section for z scores of a range of confidence levels. Thus, for the case above, a sample size of at least 385 people would be necessary.

How do you find the sample size of a known population?

n = N*X / (X + N – 1), where, X = Zα/22 *p*(1-p) / MOE2, and Zα/2 is the critical value of the Normal distribution at α/2 (e.g. for a confidence level of 95\%, α is 0.05 and the critical value is 1.96), MOE is the margin of error, p is the sample proportion, and N is the population size.

How do you find the sample size for a sample mean?

First multiply the critical value by the standard deviation. Then divide this result by the error from Step 1. Now square this result. This result is the sample size.

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Why is sample size 385?

Sample Size = 385 If we were to increase that population size to 5 million or even 5 billion, the sample size would still be 385.

How do you find the sample size for a confidence interval?

How to Find a Sample Size Given a Confidence Level and Width (unknown population standard deviation)

  1. za/2: Divide the confidence level by two, and look that area up in the z-table: .95 / 2 = 0.475.
  2. E (margin of error): Divide the given width by 2. 6\% / 2.
  3. : use the given percentage. 41\% = 0.41.
  4. : subtract. from 1.

What is the minimum sample size needed for a 90 confidence interval?

1.645
For example, the area between z*=1.28 and z=-1.28 is approximately 0.80….In This Article.

Confidence Level z*-value
90\% 1.645 (by convention)
95\% 1.96
98\% 2.33
99\% 2.58

How do we calculate sample size?

5 Steps for Calculating Sample Size

  1. Specify a hypothesis test.
  2. Specify the significance level of the test.
  3. Specify the smallest effect size that is of scientific interest.
  4. Estimate the values of other parameters necessary to compute the power function.
  5. Specify the intended power of the test.
  6. Now Calculate.
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