margin of error

  1. D

    Political Polling: Sample Size and Margin of Error

    Hello, My country have a proportional/majority system. I wonder how can a poll have a margin of error of 2.0%, if all the regional samples used in the poll have a bigger margin of error? - Southwest Region: N~64MM, n=880 and E~3.5%; - Northwest Region: N~39MM, n=553 and E~4.5%; - Central...
  2. G

    Construct a 95% confidence interval for the population proportion of all students...

    A researcher wants to know what proportion of all students who have completed a course in Statistics do not have a solid understanding of what a Sampling Distribution is. A random sample of 320 students who recently completed a Statistics course were given a basic exam on Sampling Distributions...
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    How do you create an acceptance criteria range for multiple populations?

    I am trying to create a quality control acceptance criteria range for my company's product. So here is an example of my problem: A car is traveling on a straight road and through scientific studies, I am able to predict the distance where the car will travel at a fixed time. From...
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    Confidence level and Margin of Error applied to Satisfaction surveys

    Hello, New to the forum, relatively new to stats as well! So I think I've managed to confuse myself and am going around in circles with this, so help would be appreciated. I'll outline what i'm trying to achieve and what data I have available below: So, i'm sending out satisfaction surveys...
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    Just some homework help

    Hey all. I'm a high school student taking a stats class and could use some help because i can't seem to understand how to do this question without knowing the standard deviation. If you could post how you did it, that would be awesome! The question is: In a survey of 9700 T.V. viewers, 40%...
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    Net Promoter Score - Calculating Confidence Intervals and Margin of Error

    Hello, In my sample of 1162, I have 291 Promoters, 476 Neutral and 395 Detractors. I therefore have an NPS of -9. We have calculated a confidence interval of 4.4. Question : Should this be reported as -9 +/-4.4, or is the confidence interval the entire range, in which case it should be...
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    Sample size determination (margin of error)

    Hi all, I notice my organization does not follow to NIST standards and I seek for help from the community: All the while, my company has been using the following; and I am often confused on the validity: The binomial equation used to predict the probability of a specific number of r...
  8. J

    Basic Sample Sizing Question

    Hi all, I haven't done any stats for a long time, I am looking to incorporate some stats into my Ops Risk role to get a little edge. I think I am on the right track with this first little attempt but just wanted to run it by the forum for any feedback. So at work, we are starting a new...
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    statistics question re margin of error, standard deviation

    I took a test for which the score range was 70-130. A score of 100 represents the average score of my peer group. The standard deviation was 15. My score was 105. I am wondering how accurate the test is, i.e. would a score of 100 in a hypothetical perfectly devised test be truly anywhere...
  10. J

    Calculating margin of error in participant's accuracy for multiple choice questions

    Dear forum, I have administered a listening test where 25 participants listened to comparisons of two audio samples (96 comparisons in the first block, and 48 in the second block) and answered a question whether they thought: 1. sound A was louder than sound B 2. sound B was louder than...
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    No margins for chi-squared test with multiple categories?

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    Impact of high MOE among sub-groups

    Hello, I have a question and I'm hoping someone could help me figure out. I will give an example of what I'm coming across, so this is not a "real" example... Let's say I have 10 regions in my sample. In each of these regions, there is n=10 so I certainly will not look at the data on a...
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    Margin of error for stratified survey sample

    Hi all, apologies for cross-posting: I posted this in another forum last week; it received over 100 views but no responses! I have a stratified sample of respondents to a survey with the following make-up: So the total population is 7468 (and the total sample size is 1,008). I have also...
  14. S

    Margin of error for stratified survey sample

    Hi all, first-time poster here. I have a stratified sample of respondents to a survey with the following make-up: So the total population is 7468 (and the total sample size is 1,008). I have also applied a set of weights to the data, which yields the following effective sample...
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    Calculating margin of error

    Hi, I carried out a survey of a small population (70 people) and obtained 36 completed questionnaires, representing a response rate of just over 50%. I calculated the margin of error (at 95% CI) as 0.98/square root of 36 = 0.16. I am wondering if this is correct as I didn't sample from...
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    Combining standard deviation/normal distribution (do I have this right?)

    I have a variable with a mean of 52% and a standard deviation of 2.5%. However, the 52% mean was derived from an opinion poll which itself has a 3% margin of error, which I take to imply a standard deviation of 1.53%. Assuming a normal distribution I can calculate from the former a 21% chance of...