How To Calculate Margin Or Error Statistics
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Margin Of Error Formula Algebra 2
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Margin Of Error Formula For Sample Size
Sample Mean Related Book Statistics For Dummies, 2nd Edition By Deborah J. Rumsey When a research question asks you to find a statistical sample mean (or average), you need to report a margin of error, or MOE, for the sample mean. The general formula for the margin of error for the sample mean (assuming a certain condition is met -- see
Margin Of Error Definition
below) is is the population standard deviation, n is the sample size, and z* is the appropriate z*-value for your desired level of confidence (which you can find in the following table). z*-Values for Selected (Percentage) Confidence Levels Percentage Confidence z*-Value 80 1.28 90 1.645 95 1.96 98 2.33 99 2.58 Note that these values are taken from the standard normal (Z-) distribution. The area between each z* value and the negative of that z* value is the confidence percentage (approximately). For example, the area between z*=1.28 and z=-1.28 is approximately 0.80. This chart can be expanded to other confidence percentages as well. The chart shows only the confidence percentages most commonly used. Here are the steps for calculating the margin of error for a sample mean: Find the population standard deviation and the sample size, n. The population standard deviation, will be given in the problem. Divide the population standard deviation by the square root of the sample size. gives you the standard error. Multiply by the appropriate z*-value (refer to the above table). For example, the z*-valu
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Margin Of Error Sample Size
Calculator Permutation Calculator / Combination Calculator Interquartile Range Calculator Linear Regression Calculator Expected Value Calculator Binomial Distribution Calculator Statistics Blog Calculus how to find confidence interval Matrices Practically Cheating Statistics Handbook Navigation How to Calculate Margin of Error in Easy Steps Probability and Statistics > Critical Values, Z-Tables & Hypothesis Testing > How to Calculate Margin of Error Contents (click to http://www.dummies.com/education/math/statistics/how-to-calculate-the-margin-of-error-for-a-sample-mean/ skip to that section): What is a Margin of Error? How to Calculate Margin of Error (video) What is a Margin of Error? The margin of error is the range of values below and above the sample statistic in a confidence interval. The confidence interval is a way to show what the uncertainty is with a certain statistic (i.e. from a poll or survey). For example, a poll might state http://www.statisticshowto.com/how-to-calculate-margin-of-error/ that there is a 98% confidence interval of 4.88 and 5.26. That means if the poll is repeated using the same techniques, 98% of the time the true population parameter (parameter vs. statistic) will fall within the interval estimates (i.e. 4.88 and 5.26) 98% of the time. What is a Margin of Error Percentage? A margin of error tells you how many percentage points your results will differ from the real population value. For example, a 95% confidence interval with a 4 percent margin of error means that your statistic will be within 4 percentage points of the real population value 95% of the time. The Margin of Error can be calculated in two ways: Margin of error = Critical value x Standard deviation Margin of error = Critical value x Standard error of the statistic Statistics Aren't Always Right! The idea behind confidence levels and margins of error is that any survey or poll will differ from the true population by a certain amount. However, confidence intervals and margins of error reflect the fact that there is room for error, so although 95% or 98% confidence with a 2 percent Margin of Error might sound like a very good statistic, room for error is built in, whi
a Sample Size Do We Need for a… 3 What Is a Confidence Interval? 4 How to Calculate a Confidence Interval for a… 5 Calculating a Confidence Interval for a http://statistics.about.com/od/Inferential-Statistics/a/How-To-Calculate-The-Margin-Of-Error.htm Mean About.com About Education Statistics . . . Statistics Help and Tutorials by Topic Inferential Statistics How to Calculate the Margin of Error What Is the Margin of Error for an Opinion http://stats.stackexchange.com/questions/18603/how-can-i-calculate-margin-of-error-in-a-nps-net-promoter-score-result Poll? Share Pin Tweet Submit Stumble Post Share By Courtney Taylor Statistics Expert By Courtney Taylor Many times political polls and other applications of statistics state their results with a margin of error. margin of It is not uncommon to see that an opinion poll states that there is support for an issue or candidate at a certain percentage of respondents, plus and minus a certain percentage. It is this plus and minus term that is the margin of error. But how is the margin of error calculated? For a simple random sample of a sufficiently large population, the margin or margin of error error is really just a restatement of the size of the sample and the level of confidence being used.The Formula for the Margin of ErrorIn what follows we will utilize the formula for the margin of error. We will plan for the worst case possible, in which we have no idea what the true level of support is the issues in our poll. If we did have some idea about this number , possibly through previous polling data, we would end up with a smaller margin of error.The formula we will use is: E = zα/2/(2√ n) continue reading below our video 5 Common Dreams and What They Supposedly Mean The Level of ConfidenceThe first piece of information we need to calculate the margin of error is to determine what level of confidence we desire. This number can be any percentage less than 100%, but the most common levels of confidence are 90%, 95%, and 99%. Of these three the 95% level is used most frequently.If we subtract the level of confidence from one, then we will obtain the value of alpha, written as α, needed for the formula.The Critical ValueThe next step in calculati
Tour Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Cross Validated Questions Tags Users Badges Unanswered Ask Question _ Cross Validated is a question and answer site for people interested in statistics, machine learning, data analysis, data mining, and data visualization. Join them; it only takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top How can I calculate margin of error in a NPS (Net Promoter Score) result? up vote 14 down vote favorite 16 I'll let Wikipedia explain how NPS is calculated: The Net Promoter Score is obtained by asking customers a single question on a 0 to 10 rating scale, where 10 is "extremely likely" and 0 is "not at all likely": "How likely is it that you would recommend our company to a friend or colleague?" Based on their responses, customers are categorized into one of three groups: Promoters (9–10 rating), Passives (7–8 rating), and Detractors (0–6 rating). The percentage of Detractors is then subtracted from the percentage of Promoters to obtain a Net Promoter score (NPS). NPS can be as low as -100 (everybody is a detractor) or as high as +100 (everybody is a promoter). We have been running this survey periodically for several years. We get several hundred responses each time. The resulting score has varied by 20-30 points over the course of time. I'm trying to figure out which score movements are significant, if any. If that simply proves too difficult, I'm also interested in trying to figure out the margin of error on the basics of the calculation. What's the margin of error of each "bucket" (promoter, passive, detractor)? Maybe even, what's the margin of error if I just look at the mean of the scores, reducing the data to just one num