# Tagged Questions

99 views

### sample size to get 99.6% confidence on a one-tailed test

If I have a normally distributed population of 3.5 million elements, and I want to sample enough of them to make a statement with 99.6% confidence on a 1-tailed test, what should my sample size be? ...
165 views

### Does it make sense to compute confidence intervals and to test hypotheses when data from whole population is available?

Does it make sense to compute confidence intervals and to test hypotheses when data from whole population is available? In my opinion, the answer is no, since we can accurately compute true values of ...
161 views

### Incorporating the effect of sample size in maximum likelihood estimation

I have two sample sets that consist of independent trials of a binomial variable X = {X0, X1}. For the remainder, I denote the probabilities as ...
87 views

### How to add prediction intervals to describe the variability in monthly samples of data?

The data analyzed here is a sample of individuals collected on a monthly basis. What would be the best way to compute "prediction intervals" for the monthly sample means, in order to indicate the ...
272 views

### How do I calculate sample size so I can be confident that the sample mean approximates the population mean?

Unfortunately, it's a long while since I did statistics and despite reading & research I'm not 'confident' as to how to calculate this correctly. I would like to know the smallest sample size ...
52 views

### Sample size for Wilson's confidence interval

Consider a story ranking website in which the ranking is crowd sourced from the number of up votes and down votes received by a story. The score is computed as the lower bound Wilson's algorithm. ...
183 views

### How does the confidence interval for the parameter p of a bernoulli trial vary with the value of p itself?

This is a very basic question (I'm currently studying undergrad level statistics), but I was hoping for some clarification regarding an assertion I read in a newspaper article earlier today. The ...
386 views

### How to quantify the significance of the difference between two z-scores?

I have one sample and several features. I calculate a z-score for various features, and for various combinations of features. Is there a way to quantify the significance of the difference between ...
56 views

### How big is n in a weighted portfolio?

I want to identify the relevance of some results. So far I have done some reading and have understood the following: I'd like to prove the meaning from my final results, and I want to evaluate the ...
109 views

### Minimum sample size determination for difference of two normally distributed populations

This is homework, but I am rather stuck and the TA for the class has yet to make his solutions. Any help with moving me in the proper direction would be most appreciated. I am having some difficulty ...
247 views

### How does confidence interval vary with sample size?

I am trying to convert state-level poll results for 2012 U.S. presidential election into state-level probabilities of each candidate winning. To achieve that, I am using the logistic function, which ...
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### How is it that the required sample size for a specified error and confidence is not dependent on population size? [duplicate]

Possible Duplicate: Why does standard error not involve population size? When calculating confidence intervals for population parameters, the population size is never a factor, rather ...
892 views

### Confidence intervals vs sample size?

I am totally new to stats and the field of confidence intervals. So this might be very trivial or even sound stupid. I would appreciate if you could help me understand or point me to some ...
118 views

### Sample size when one hypothesis is overwhelming

I am looking at a situation where I have a population of about 150-170. I am testing for the absence or presence of a particular property. Given the population, I can easily figure out the sample size ...
502 views

### Can I compute a confidence level for a z-test based on the size of the samples?

I'm doing a two sample z-test for the difference between means using pooled variance. Suppose I've run two experiments. In the first experiment, the sample size for the two populations is only 100, ...
454 views

### Minimum sample size to achieve a specific confidence level and interval

I am building software components that are going to be used by multiple users simultaneously. At the current point in time, these components are known bad. That is, if I simulate multiple users ...
487 views

### Sample size for binomial confidence interval

Background: A group at work is sampling 1,000 customers to contact and from that point, determining if the effort is worthwhile or not. I wanted to see if this (pretty much) arbitrary sample size ...
398 views

### How to adjust average rating for sample size on rating systems with more than two categories?

After reading How Not To Sort By Average Rating which deals with confidence interval for a Bernoulli parameter how would you extend it to more than two levels? For example: Items are scored between 1 ...
199 views

### How do I compute a confidence level for a forced ranking survey?

How do I compute a confidence level for a forced ranking survey? For example, say I have 10 categories, each with four associated statements that must be ranked either 1, 2, 3 or 4 with no duplicate ...
80 views

### Significance of multinomial data [duplicate]

Possible Duplicate: Sample size for a variable number of answers I have data which was generated from a (theoretical) multinomial distribution, and using the data points I estimate the ...
1k views

### Determining sample size for uniform distribution

May you help me to decide what is the minimal sample size for a uniform distributed sample. Assume that I've find the sample average, standard deviation and the $\alpha$.
272 views

### Sample size for a variable number of answers

I have N different possible results (ex. red, yellow, or blue). I go to a population of infinite size and ask a bunch of people a question the answer to which is one of the N options.... How large ...
582 views

### Statistical significance when A/B test has multiple values

I'm sure this is a pretty standard statistics question, but I'm no expert... I'm running an A/B test on my website to see if a change results in users adding more content. So there are 2 basic ...