Multiply the sample proportion by Divide the result by n. share|improve this answer answered Jun 29 '15 at 20:12 whuber♦ 145k17283542 Thanks! They asked whether the paper should increase its coverage of local news. The variability of a statistic is measured by its standard deviation.

up vote 3 down vote favorite I know the "textbook" estimate of the standard error of a proportion is $SE=\sqrt{\frac{p(1-p)}{n}}$, but does this hold up when the data are weighted? Do NOT round the value for p hat and use the rounded value in the calculations. The Z here is the z-score obtained from the normal table, or the bottom of the t-table as explained in the introduction to estimation. Stat Trek Teach yourself statistics Skip to main content Home Tutorials AP Statistics Stat Tables Stat Tools Calculators Books Help Overview AP statistics Statistics and probability Matrix algebra Test preparation

Suppose we take a sample of 40 graduating students, and suppose that 6 out of the 40 are planning to go to graduate school. And since the population is more than 20 times larger than the sample, we can use the following formula to compute the standard error (SE) of the proportion: SE = sqrt Stat Trek Teach yourself statistics Skip to main content Home Tutorials AP Statistics Stat Tables Stat Tools Calculators Books Help Overview AP statistics Statistics and probability Matrix algebra Test preparation Use the sample proportion to estimate the population proportion.

If 54 out of 360 students plan to go to graduate school, the proportion of all students who plan to go to graduate school is estimated as ________. Physically locating the server Is it possible to have a planet unsuitable for agriculture? (KevinC's) Triangular DeciDigits Sequence In the United States is racial, ethnic, or national preference an acceptable hiring A sample proportion is the decimal version of the sample percentage. Under these circumstances, use the standard error.

Sample Planning Wizard As you may have noticed, the steps required to estimate a population proportion are not trivial. Compute margin of error (ME): ME = critical value * standard error = 2.58 * 0.012 = 0.03 Specify the confidence interval. Resources by Course Topic Review Sessions Central! b.

The resulting quantity is called the estimated standard error of the sample proportion . Use the sample proportion to estimate the population proportion. The standard error (SE) can be calculated from the equation below. Often, researchers choose 90%, 95%, or 99% confidence levels; but any percentage can be used.

III. The standard error can be computed from a knowledge of sample attributes - sample size and sample statistics. In the example of a poll on the president, n = 1,000, Now check the conditions: Both of these numbers are at least 10, so everything is okay. Compute alpha (α): α = 1 - (confidence level / 100) = 1 - (99/100) = 0.01 Find the critical probability (p*): p* = 1 - α/2 = 1 - 0.01/2

From the previous section, the SD of equals . Since we do not know the population proportion, we cannot compute the standard deviation; instead, we compute the standard error. Therefore, the 99% confidence interval is 0.37 to 0.43. Population parameter Sample statistic N: Number of observations in the population n: Number of observations in the sample Ni: Number of observations in population i ni: Number of observations in sample

Standard Error of Sample Estimates Sadly, the values of population parameters are often unknown, making it impossible to compute the standard deviation of a statistic. In other words, if you have a sample percentage of 5%, you must use 0.05 in the formula, not 5. But if the population proportion were extreme (i.e., close to 0 or 1), a much larger sample would probably be needed to produce at least 10 successes and 10 failures. That is, the 99% confidence interval is the range defined by 0.4 + 0.03.

The sample is sufficiently large. Keep in mind that the margin of error of 4.5% is the margin of error for the percent favoring the candidate and not the margin of error for the difference between They can be time-consuming and complex. The confidence interval is computed based on the mean and standard deviation of the sampling distribution of a proportion.

And the uncertainty is denoted by the confidence level. The value of Z.95 is computed with the normal calculator and is equal to 1.96. Stat Trek's Sample Planning Wizard does this work for you - quickly, easily, and error-free. On the TI-82, a good choice would be the letter E.

In this situation, a sample size close to 100 might be needed to get 10 successes. Approximate Value − Exact Value × 100% Exact Value Example: They forecast 20 mm of rain, but we really got 25 mm. 20 − 25 25 × 100% = −5 25 Refer to the above table for the appropriate z*-value. Select a confidence level.

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