sampling design

  1. rogojel

    Regular Sampling

    hi, I had the following question and I really wonder if I gave the right answer: Assume that you can measure a process once a day ( for the sake of an example assume sampling the quality of water from a stream). Does it make sense to sample at random time points or is it enough to sample...
  2. V

    Experimental Design/Need help reviewing my answers

    I am having difficulties with questions below. I know I have a couple of them wrong, but I am not sure which one. I keep going over and over trying to figure out which one to change. :confused: Below are my answers in bold. Thank you Question 2 Jon believes that coursing...
  3. E

    random sampling of unequal size structures

    Hi, I had a student come to me for help on his thesis in materials engineering. He is interested in studying the distribution of pore sizes in a sample of material. The main problem I saw with his methodology was that he did not have any random sampling methodology for choosing the pores he...
  4. 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...
  5. 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.
  6. G

    Stratification criteria mess up the use of a random factor?

    Hi! In my study on kelp I want to see how wave exposure and current (both continuous variables) affect kelp physical measures along the Norwegian coast. To assure a balanced design, I stratified my study area into 9 different classes, defined by all combinations of three levels of wave...