# Margin Of Error And Sample Proportion

## Contents |

In Lesson 9 we learned what **probability has to say about how** close a sample proportion will be to the true population proportion.In an unbiased random surveysample proportion = population proportion How to Compute the Margin of Error The margin of error can be defined by either of the following equations. For example, the area between z*=1.28 and z=-1.28 is approximately 0.80. We call this estimate the standard error of the sample proportionStandard Error of Sample Proportion = estimated standard deviation of the sample proportion =\[\sqrt{\frac{\text{sample proportion}(1-\text{sample proportion})}{n}}\]Example 10.1The EPA considers indoor radon navigate here

COCCmath 636 views 6:46 Margin of Error Example - Duration: 11:04. How many individuals should we sample? (In the last poll his approval rate was 72%). Since we do not know p, we use .5 ( A conservative estimate) We round 425.4 up for greater accuracy We will need to drop at least 426 computers. According to sampling theory, this assumption is reasonable when the sampling fraction is small.

## Margin Of Error Formula

When estimating a mean score or a proportion from a single sample, DF is equal to the sample size minus one. You now have the standard error, Multiply the result by the appropriate z*-value for the confidence level desired. MathWorld.

For example, suppose we wanted to know the percentage of adults that exercise daily. This maximum only applies when the observed percentage is 50%, and the margin of error shrinks as the percentage approaches the extremes of 0% or 100%. References[edit] Sudman, Seymour and Bradburn, Norman (1982). Margin Of Error Definition eHowEducation 6,671 views 1:57 How to calculate Confidence Intervals and Margin of Error - Duration: 6:44.

b. Margin Of Error Calculator The area between each z* value and the negative of that z* value is the confidence percentage (approximately). Introductory Statistics (5th ed.). Watch Queue Queue __count__/__total__ Find out whyClose Margin of Error Sample Proportion StraightA Stats SubscribeSubscribedUnsubscribe1111 Loading...

It turns out that 49 of the 50 homes in our sample have a refrigerator. Sampling Error Formula a. ISBN 0-87589-546-8 Wonnacott, T.H. To change a percentage into decimal form, simply divide by 100.

## Margin Of Error Calculator

Construct a 95% confidence interval for the proportion of Americans who believe that the minimum wage should be raised. https://onlinecourses.science.psu.edu/stat500/node/31 a 40% response rate) then we would need to sample (\frac{7745}{0.4})=19,362.5 or 19,363. Margin Of Error Formula mathtutordvd 125,382 views 8:53 WHAT IS A "SAMPLING DISTRIBUTION" and how is it different from a "sample distribution"... Margin Of Error Confidence Interval Calculator When a single, global margin of error is reported for a survey, it refers to the maximum margin of error for all reported percentages using the full sample from the survey.

MadonnaUSI 49,415 views 9:42 Stats: Sampling Distribution of a Proportion and Standard Error - Duration: 16:52. check over here The sample size needed is 7745 people (we always need to round up to the next integer when the result is not a whole number). Loading... The sample size obtained from using the educated guess is usually smaller than the one obtained using the conservative method. Margin Of Error Excel

Close Yeah, keep it Undo Close This video is unavailable. To compute the margin of error, we need to find the critical value and the standard error of the mean. statslectures 76,137 views 4:18 Margin of Error Sample Size TI-83+ - Duration: 11:16. his comment is here Retrieved 2006-05-31. ^ Isserlis, L. (1918). "On the value of a mean as calculated from a sample".

Find the degrees of freedom (DF). How To Find Margin Of Error With Confidence Interval Thus, the maximum margin of error represents an upper bound to the uncertainty; one is at least 95% certain that the "true" percentage is within the maximum margin of error of Stephanie Glen 13,073 views 3:43 Q2b - 95% Margin of Error for a Population Proportion - Project Maths 2013 Sample Paper 2 - Duration: 5:06.

## In other words, our actually sample size would need to be 19,363 given the 40% response rate.

Contents 1 Explanation 2 Concept 2.1 Basic concept 2.2 Calculations assuming random sampling 2.3 Definition 2.4 Different confidence levels 2.5 Maximum and specific margins of error 2.6 Effect of population size How to Find the Critical Value The critical value is a factor used to compute the margin of error. Loading... How To Find Margin Of Error On Ti 84 The size of the sample was 1,013.[2] Unless otherwise stated, the remainder of this article uses a 95% level of confidence.

Loading... If the confidence level is 95%, the z*-value is 1.96. Loading... weblink Category Education License Standard YouTube License Show more Show less Loading...

What is the population value being estimated by this sample percentage? To find the critical value, we take the following steps. Refer to the above table for the appropriate z*-value. headlessprofessor 45,662 views 6:17 Confidence Intervals Part I - Duration: 27:18.

Census Bureau. When the sampling distribution is nearly normal, the critical value can be expressed as a t score or as a z score. Retrieved on 2 February 2007. ^ Rogosa, D.R. (2005). This could get expensive.

Because we are estimating the smallest sample size needed to produce the desired error. If you want a 90% confidence interval for this proportion, with a margin of error of 4%, How many computers should you drop? 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 At the Centre Community Hospital is State College, Pennsylvania, it is observed that 185 out of 360 babies born last year were girls.

Brandon Foltz 56,389 views 27:15 Margin of Error - Duration: 6:17. To find the critical value, follow these steps. If the statistic is a percentage, this maximum margin of error can be calculated as the radius of the confidence interval for a reported percentage of 50%. Or, if you calculate a 90% confidence interval instead of a 95% confidence interval, the margin of error will also be smaller.

MrNystrom 153,397 views 15:40 Confidence Intervals (Z-Intervals) - Duration: 9:59. About Press Copyright Creators Advertise Developers +YouTube Terms Privacy Policy & Safety Send feedback Try something new! Created by Sal Khan.ShareTweetEmailEstimating a population proportionConfidence interval exampleMargin of error 1Margin of error 2Next tutorialEstimating a population meanTagsConfidence intervalsConfidence interval exampleMargin of error 2Up NextMargin of error 2 Watch Queue Queue __count__/__total__ Find out whyClose How to calculate Margin of Error Confidence Interval for a population proportion statisticsfun SubscribeSubscribedUnsubscribe50,66250K Loading...

Lesson 10 - Have Fun With It! Warning: If the sample size is small and the population distribution is not normal, we cannot be confident that the sampling distribution of the statistic will be normal.