stratified sampling

1. Test & Control File Selection - Help

Hi all I hope all is great with everyone. I'm new on here so sorry to get straight down to my query and hope that someone might be able to point me in the right direction. Thank you. So: I have a prospects direct mail file and I'm testing a new message, (One change). To ensure it’s the...
2. Regression with stratified data: What to do?

Hi, I want to model a bird population in a country via regression analysis (Poisson regression due to count data). In order to optimize the sampling effort versus precision, I use a stratified random design: The country is splitted into 10 different habitats, and from each habitat I draw...
3. Combining two samples to then do Cluster Analysis/multivariate analysis

I was wondering if someone can help. For a university assignment I have been asked to propose a marketing research method & survey etc for a company. I have been set an online takeaway website to do. We are asked in the survey to find out about food habits and the takeaway market. Survey has...
4. Margin of error for stratified survey sample

Hi all, apologies for cross-posting: I posted this in another forum last week; it received over 100 views but no responses! I have a stratified sample of respondents to a survey with the following make-up: So the total population is 7468 (and the total sample size is 1,008). I have also...
5. Margin of error for stratified survey sample

Hi all, first-time poster here. I have a stratified sample of respondents to a survey with the following make-up: So the total population is 7468 (and the total sample size is 1,008). I have also applied a set of weights to the data, which yields the following effective sample...
6. Help! should I use svy: logit or xtlogit random effect for stratified cluster RCT?!

Hi, I'm analysing some secondary outcome data from a cluster RCT and I don't know whether to do it using svyset and then svy: logistic or whether to do xtlogit , or i(cluster) re ...they give very different odds ratios and so i do need to know which is correct! The trial design is as...
7. [Matlab] - Stratified Sampling of Multidimentional Data

I want to divide a corpus into training & testing sets in a stratified fashion. The observation data points are arranged in a Matrix A as A=[16,3,0;12,6,4;19,2,1;.........;17,0,2;13,3,2] Each column of the matrix represent a distinct feature. In Matlab, the cvpartition(A,'holdout',p)...
8. Sample Size calculations with sub-groups

I am in a situation wher we need to recruit 1600 people with a particular condition (calculated so that we can detect a 5% change following intervention). We also want to test the intervention on a particular sub-type (drug-users), where we expect a higher prevalence of the condition, and want...
9. 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...
10. 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...
11. How to design the sampling plan?!

I need to conduct an investigate in my province, we need to investigate the Scientific literacy of people in our province. The sampling plan I design is: 1. sampling the cities in our province. 2. sampling the countries in the cities. 3. sampling the families in the countries. 4. sampling...
12. obtaining β(hat)s from weighted least square regression

I'm doing Regression analysis under stratified random sampling for my research since it's usually assumed in many textbooks that the data is simple random sampling.. so in my case it would be stratified sampling.. How do you get the β(hat) ̂from a WLS Regression under a stratified random...