Linked Questions

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0answers
78 views

What is the estimate of sample mean variance? [duplicate]

Possible Duplicate: How does the standard error work? What is the estimate of sample mean variance and how do you get it? Are my understandings of the following correct? $var(Y)=\frac{1}{N} \sum ...
0
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2answers
47 views

Variance calculation [duplicate]

Can someone explain why: Given a set of n independent observations Z1...Zn, each with variance K. The variance of the mean is K/n?
0
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0answers
45 views

Very easy question : Sample Variance [duplicate]

Possible Duplicate: How does the standard error work? Let's say I have an unbiased estimator, which is the sample mean, to estimate $\theta$. When can you say that $$VAR[\overline{X}] = \frac{\...
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0answers
22 views

How do I add a “confidence rating” to something? [duplicate]

I have a bunch of survey responses from people all over the country. Each survey has one question: "How much do you like X?" (X isn't important here), where answers range from 0 (not at all) to 100 (a ...
0
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0answers
19 views

Standard error, margin of error, polls and binomial distribution [duplicate]

So, when doing polling, we use binomial distribution to capture the data (in case there are only two choices.). My question is, let us say that estimated percentage according to the poll that ...
0
votes
0answers
15 views

Standard error for expected value [duplicate]

I have a computer simulation from which I get a sample of values of some microscopic quantity $X$, i.e. $\{ x_1,\ldots,x_N \}$. I'm interested in estimating the expected value of $X$, i.e. $E[ X]\...
30
votes
5answers
6k views

Strategies for teaching the sampling distribution

The tl;dr version What successful strategies do you employ to teach the sampling distribution (of a sample mean, for example) at an introductory undergraduate level? The background In September I'll ...
21
votes
3answers
22k views

How can I calculate margin of error in a NPS (Net Promoter Score) result?

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 "...
11
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2answers
11k views

What is the null hypothesis of a MANOVA?

Background In order to analyze differences in some continuous variable between different groups (given by a categorical variable), one can perform a one-way ANOVA. If there are several explanatory (...
3
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3answers
10k views

Why compare sum of squares with ANOVA (and not mean)?

I got the following result of a ANOVA analysis of five independent variables with 5,8,2,2,6 levels and 5 replications for each combination: ...
2
votes
3answers
1k views

Standard error of a population

I measure the weight of 100 people and pick 20 lots of 5 people from these 100. Therefore n = 5, repeated 20 times. The 100 people represent the population and groups of 5 people represent samples ...
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1answer
302 views

What does the standard error of my IV estimate tell me?

I have computed the IV estimate and the standard error of the IV estimate. Why do I care about its standard error?
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0answers
656 views

Understanding standard error of the mean

Wikipedia article about standard error It's clear to me that the formula $${SD}_\bar{x}\ = \frac{\sigma}{\sqrt{n}}$$ is equal to the true standard deviation of the sample mean, given that $\sigma$ ...
3
votes
1answer
123 views

Are degrees of freedom $n-1$ for both the sample standard deviation of the individual observations and for the standard error of the sample mean?

I collect $n$ ($<20$) i.i.d. observations from any distribution. In order to compute the sample variance, I take $$s^2=\sum_i \frac{(\bar{X}-X_i)^2}{n-1}$$ If I want to build a confidence ...
0
votes
1answer
62 views

Sampling Distribution [closed]

Suppose $X \sim N(\mu, \sigma^2)$. After $n$ independent draws $\bar{X} \sim N(\mu, \frac{\sigma^{2}}{n})$. I am assuming that each draw contains $n$ numbers? Because if each draw only had one number ...

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