bootstrap

  1. E

    Logistic regression, sample sizes and bootstraping

    Hello, this is my first post. I currently I'm working in my phD in a multivariate logistic model but I have a problem regarding the sample size of my observations: -The "success" (1) event group has a sample size of 249 distinct observations - The "non success" (0) event group has a sample size...
  2. U

    Testing heteroskedasticity in a bootstrapped quantile regression

    Hi, I am currently using stata to perform some regressions, and need help on how to perform specific tests on bootstrapped quantile regressions. I have a dataset with 31variables, most of which are dummies, and 1600 obs. I am looking to perform quantile regressions as the distribution is...
  3. amsavage

    bootstrap estimates with summary data

    I feel like this may be a silly question, but pride aside: If you only have access to summary data (cov matrix, means and SD) can you still generate bootstrap estimates in AMOS? I think the answer is likely 'not without raw data' but I would like to see if any other ideas exist out there on...
  4. rogojel

    Using bootstrap to calculate the sample size for a median ?

    hi, I have a small(ish) sample of 31 data points from a highly right skewed distribution and need to determine the sample size to estimate the median. My idea is to randomly select (with replacement) 10 data points and then estimate with the bootstrap the 0,025 and 0.975 percentiles and...
  5. Y

    Bootstrap and more

    Hi guys, I've 2 questions:
  6. F

    Reference to justify the use of bootstrap

    Dear all, My colleagues and I conducted a research involving a dichotomous outcome (i.e., the detection of an unexpected event in a particular scenery). We assigned participants randomly in one out of three condition. Our hypothesis is that one of this condition will increase the detection...
  7. D

    Comparison of variability of synthetic and real data

    Hello, I'm trying to compare a real dataset with a random (synthetic) distribution to determine whether a pattern I see in the data is real or the result of a random distribution or poor sampling. I've been struggling with this problem for weeks and no number of websites or books are...
  8. C

    Help! WLS + Bootstrap

    Hello everyone, I would like to do a weighted-least-squares regression through a nonparametric bootstrap in stata. Does anybody know how this might work? The "vce(bootstrap.." command does not work in combination with a "wls0" command Thanks in advance! CheersToStata
  9. C

    Paired bootstrapping

    Hey everyone! Absolute newbie to R, would appreciate help with a question I have been struggling with. Let's say I want to test the efficacy of a medicine in reducing blood pressure. So I have a paired sample . Three vectors are created in r. Before <-c(129,135,145,89,70) and after...
  10. trinker

    Correlation pvalue from a bootstrap

    I'm working through some machine learning stuff that deals with simulation/bootstrapping and come across a point where a pvalue is calculated but not how it was calculated. This is precisely the type of work I'm moving towards so I want to understand how to do it. Here's what the author of the...
  11. R

    how to get adjusted means in Stata complex survey (e.g. svy commands)

    Hi, I am running generalized linear models using the stata (version 13) complex survey commands and my analyses use survey weights and bootstrap weights. I would like to know how to get adjusted means values for the 3 levels of my independent variable (which is a categorical variable)...
  12. victorxstc

    Bootstrapped binary logistic regression in R

    I am trying to run a bootstrapped binary logistic regression. I have loaded the dataset manually into Rstudio (don't know the syntax yet! actually the syntax I learned from Rcommander didn't work in Rstudio); and here is my code for the bootstrapped regression (thanks to this site): (the...
  13. M

    [Statistica] Command for percentile / bootstrap

    I am trying to get 0.05percentiles (median 095 CI) out of the bootstrap procedure in Statistica. I found the following command for median of my population: > Use file name > Sample boot(perm number,number of samples)/ median confi = 0.95 > Cstatistics variables Can anyone suggest what...
  14. K

    Bootstrapping with One-way ANOVA design and confidence interval

    Hello, I am new to this forum, and I need some helps in bootstrapping. I am using Matlab. So, here's the study design: I have three groups (Group1, Group2, Group3), 30 subjects/group each. They all have some brain imaging scans (FDG-PET). Within each group, I calculated some parameter...
  15. C

    Bootstrap bias

    Good day forum, I'm using a bootstrap approach to get a better understanding of a sampling distribution. I've heard that the bootstrap approach introduces a specific bias into the results. Would anyone be so kind as to explain this to me, and how to compensate for this - or otherwise refer me...
  16. C

    Cross Validation/Bootstrap on Time Series Segement

    I have a small time series segment (~100 to ~500 points) and would like to fit a function to it. I'm not interested in the out of sample performance, but I want to make sure that I avoid overfitting. I read online that cross validation and bootstrap don't work on time series since the data are...
  17. N

    Bootstrap analysis for partial correlations

    Hello, I was hoping someone could please help or direct me to another page that explains bootstrapping with partial correlations (i.e., correlations between two variables after controlling for a third variable)? For example, correlating posttest performance with another variable (e.g., SAT...
  18. P

    Random Resampling from Nest Data

    First off, thanks for your help if you have any comments, and I apologize if there is a post about this somewhere (I was unable to find one). So, here is my problem. I need to randomly draw samples from my dataset of grouped data. I have observations in separate rows. Each participant belongs...
  19. M

    AMOS Bootstrapping - Mean Chi Square/df?

    Hi, I am working on a project modelling a variety of psychological outcomes for AIDS-affected youth in South Africa. Inevitably, some of our variables are not normally distributed, so we have used the bootstrapping procedure available in AMOS to estimate paremeters in the model...
  20. B

    Bootstrapping confidence intervals for prediction based on SE of the coefficients?

    Is it remotely legitimate to use the standard errors of the coefficients from linear regression in a Monte Carlo simulation to bootstrap 2.5%/97.5% confidence intervals on the predictions? If so (or if not), is there any literature relevant to this approach?