##### Finding Margin of error

 Statistics Tutor: None Selected Time limit: 1 Day

Assume that a random sample is used to estimate a population proportion p. FInd the margin of error E that corresponds to the given statistics and confidence level.

98% confidence, sample size 3013, of which 15% are successes.

I'm confused on how to find it

Oct 3rd, 2015

The standard error of the mean  of a binomial distribution Bi (3013, 0.15)= pq/ √n

= 0.15 × (1 - 0.15) /√3013 = 0.002322794

margin of error = 98% critical value   × standard error

= 2.33  × 0.002322794

= 0.005412

(roughly half a percentage point)

Oct 3rd, 2015

i looked and it came back that it was wrong.I'm so confused

Oct 3rd, 2015

What is the answer then because you can check from the internet the definition of margin of error and you can check the formula for standard error.

Oct 3rd, 2015

Margin of Error

In a confidence interval, the range of values above and below the sample statistic is called the margin of error.

For example, suppose we wanted to know the percentage of adults that exercise daily. We could devise a sample design to ensure that our sample estimate will not differ from the true population value by more than, say, 5 percent (the margin of error) 90 percent of the time (the confidence level).

How to Compute the Margin of Error

The margin of error can be defined by either of the following equations.

Margin of error = Critical value x Standard deviation of the statistic

Margin of error = Critical value x Standard error of the statistic

If you know the standard deviation of the statistic, use the first equation to compute the margin of error. Otherwise, use the second equation. Previously, we described how to compute the standard deviation and standard error.

Oct 3rd, 2015

sorry the standard error is

The standard error of the mean  of a binomial distribution Bi (3013, 0.15)=√ pq/ √n

= √[0.15 × (1 - 0.15)] /√3013 = 0.006505

margin of error = 98% critical value   × standard error

= 2.33  × 0.006505

= 0.01516

(roughly one percentage point)

Oct 3rd, 2015

Is it ok now.

You can ask me another question (free) using this dialogue to make up for the mistake. Sorry!

Oct 3rd, 2015

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Oct 3rd, 2015
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Oct 3rd, 2015
Dec 10th, 2016
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