sampling

  1. O

    Generating a multi-parameter space and sampling from it

    Hi all, I have a long list of combination of parameters which covary. I would like to sample from it but not exactly the same values. What I'd like to do is to create a multi-parameter space that accounts for the covariation and then sample from it the parameter values to create new...
  2. S

    OC Curve Program

    One of my friends has asked me to help him write a program to calculate the "n" and "c" values (sampling size, accept number), only given alpha(confidence level) , beta(probibility of acceptance), p1(AQL) and p2(LTPD). I'm currently a computer science major that has taken a few statistics...
  3. S

    Sample design problem

    A healthcare provider has been paid on N claims for certain health services, some of which may have been unauthorized. I must draw a sample of n claims to estimate the total payments to this provider for unauthorized claims: Y = Sum of I(k) * X(k) for k = 1 to N where: I(k) = 0 if claim k is...
  4. C

    which sampling methods-reply ASAP

    For some statistics course work, I am investigating two hypothesis', and I am not sure which sampling method I should use. They hypothesis' are: the accuracy of estimations of the size of an angle is more accurate when on white paper with black lines, and The accuracy of an estimation of the...
  5. B

    How to program a Ranked Set Sampling in R?

    I am trying to program a ranked set sampling using R. There are 2*n^2 items and I want to randomly divide them into two equal sized groups with n^2 items in each group. Then I want to use a Ranked Set Sampling from each of these groups to form n RSS blocks with n items in each RSS block. What...
  6. W

    Sampling from N data points based on a given probability distribution

    I have N data points, and each data points is associated with a probability. The sum of the N probabilities equals to one. I need to sample these N data points based on the given probability vector. Are there any algorithms that can allow me to do this kind of sampling?
  7. F

    Sampling Distributions help

    Hi, I'm teaching myself stats but have no idea on how to solve these, any help would be appreciated. When a pizza restaurant’s delivery process is operating effectively, pizzas are delivered in an average of 45 minutes with a standard deviation of 6 minutes. Suppose each night, 9 deliveries...
  8. M

    Comparing small sample to large population using ANOVA

    Hi, I have a problem I was hoping to get some help with. I am trying to evaluate the impact of an after school program on GPA, Discipline offenses, and attendance for a school district. The district has provided me with the quarterly data for each of the DVs, as well as whether or not a...
  9. P

    How does sampling reduce selection bias?

    Hi everyone, I'm struggling to understand theoretically how sampling reduces selection bias. Take the following example: Supposing there is a population of 1000 people, and 200 of them have an axe to grind (for some reason). These 200 will respond to 100% of surveys. The remaining 800 are...
  10. A

    Really Basic A level Statistics Test. (Multiple Choice)

    1) ‘Cluster sampling’ is a term given to one method of (a) Selecting random numbers using excel (b) Probabilistic sample selection (c) Snowballing (d) Downloading secondary data (e) Selecting a population 2) ‘Stratified sampling’ may provide greater precision of population...
  11. B

    simple question about sample randomness

    Thanks for looking at this. I've been given a sample of data of 105 cars. Our teacher didn't specify whether or not the sample is random, but most of the hypothesis tests I'm to perform require a random sample. I thought I could get around the possible non-randomness of the sample by taking...
  12. R

    Increasing sample size with a second sample?

    This is not a homework question but I think it is an elementary question: Say I have a simple random sample (without replacement) of 50 items from 500. Now I decided I want to increase my sample size to 60 items. I know that I can use my original seed number to generate a sample of 60 where...
  13. 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...
  14. 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.
  15. 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...
  16. 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...
  17. 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...
  18. 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...
  19. 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.
  20. 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...