1. 9

    What sampling method is this?

    Hi, I hope you can help. I collected my samples on the street by just asking passers by to fill in my questionnaire. I moved to 5 different locations within the city and spent 3 hours each visit 3 times a week for one month. Is this random sampling? Or it it sill convenience sampling? Can...
  2. D

    Design effects (or variances) of sampling methods?

    Where I can find comparison of variances (or design effect) of different sampling methods? Same population, same sample size: I want to know which one has smaller variance than other; in simple random sampling, systematic sampling, stratified sampling, cluster sampling and so on.
  3. W

    sampling issue for a data set with an embedded pattern

    I have a large set of data sets. For instance, it has 30000 data points, which are identified as 1, 2, 3,…30000. For notational purposes, D(i) represents the data value for a point identified as i. These data points have the following localized pattern, For a given integer value k...
  4. S

    Minimum stata sample size in stratification?

    Hi, I'm designing a methodology to track the effects of a price test at work, and I'm curious to know whether there are limits on how many strata I can use in a sample or on how many subjects need to be in each strata. For context, we're taking about 80-120 products (the exact number will...
  5. B

    A question about sampling

    Consider two probability distributions, A and B. A has greater variance than B, but A and B have equal means. We are not told anything about their skewness or kurtosis, these can be different for A and B (A might have fat tails or be skewed, while B might be likewise or may different all...
  6. S

    Complex Survey Design - Analysis Conundrum <- Not homework

    Hi Stats forum, So, I am the analyst for a stratified cluster sample survey. We surveyed facilities to evaluate a safety program. The survey had 5 parts. Interviewers went to the facility and staff were randomly chosen to be interviewed. Different staff were interviewed for different parts...
  7. A

    sample representativeness

    Is there a statistical test to show that a sample is representative of a population? or is just fufilling some criteria, ie sample source, data collection methods, screening criteria, etc. This is for a retrospective clinical study.
  8. J

    Alternative to chi-squared test needed

    Hi all. I need a goodness of fit test for a situation in which a chi-squared test isn't appropriate - where the sum of the expected values does not necessarily equal the sum of the observed values. For example, I have 5 cells each with the same expected value of 10. The observations for...
  9. J

    Rolling or continuous surveying or sampling

    I have been looking everywhere for an answer to this problem, so far with no luck. Hopefully the statistics gurus on this board will know the answer, here's hoping :) So I have a large population of sample data, and more coming in all the time in a continuous stream. I would like to use...