# bootstrap

1. ### Why does bootstraping with 50% samplesize and no replacements always gives appropriate confidence intervals.

Hello, I compared different ways to calculate confidence intervals. On the one side I used the direct formular on the other side I used a percentile bootstrap methoden. (Calculate the statistic (e. g. mean) on n subsamples and choose the a/2 and 1-a/2 percentile for the confidence interval.) I...
2. ### Doubt with random numbers in parametric Bootstrap

Hello all, Suppose I have a set of datas 8...20, with mean 10 and lambda 1/10=0.1 . I want to make a parametric bootstrap, supousing my datas come from an exponential distribution. So now I may construct my random samples from an exponential distribution with lambda=0.1 . My problem is I do...
3. ### Need help to correctly bootstrap confidence interval for correlation of 50 y-values against 50 averages from autocorrelated subsets of 2000 x-values

I am helping out with some plots for a paper: simple X versus Y plots, and would like to provide some stats to improve the paper. My statistics knowledge is rusty and I am an R-noob with only a few weeks of Tidyverse under my belt, so I would appreciate some input. Am I on the right track? The...
4. ### P values from bootstrap in R

I've been trying to get the pvalue of my samples from a bootstrap rsquared test in R. I'm not very good with statistics so could someone please take a look at my below code and point me in the right direction with regards to how I can extract the p-values per sample (basically input a...
5. ### Extracting p value from bootstrap

I've been trying to get the pvalue of my samples from a bootstrap rsquared test in R. I'm not very good with statistics so could someone please take a look at my below code and point me in the right direction with regards to how I can extract the p-values per sample (basically input a...
6. ### Getting p-value for rsquared bootstrap in R

I've been trying to get the pvalue of my samples from a bootstrap rsquared test in R. I'm not very good with statistics so could someone please take a look at my below code and point me in the right direction with regards to how I can extract the p-values per sample? # Bootstrap 95% CI for...
7. ### Bootstrapping with sample(), what should the size of your sub-sample be?

Hi I am currently bootstrapping my sample, x, using the sample function. sample(x, size = n, replace = T) My question is how do you know what size should be? Is there a standard procedure in determining the value of size?
8. ### How to continue raw data for Forcasting ~ Holts-Winter

Hi All, I am new to this forum and i am in need of help regarding the Holt's Winter Method. I've managed to build a forecasting model in excel using the Damped method which works very well. But due to my lack of experience, I am confused on how to continue the raw data as the forecasting...
9. ### Bootstrapping and Independent T Tests

Dear all, My question is whether it is appropriate to use Independent T Tests on distributions generated through bootstrapping. To be more specific: I used bootstrapping to generate 1000 subsamples for each of two observed distributions from different samples. I then used an SPSS macro to...
10. ### Unbalanced designs in PERMANOVA and Resampling Methods

Dear all, I am a new member here, working mainly in Ecology. I hope this is the right section to ask my question. I am dealing with unbalanced designs (I am comparing groups with different sample sizes) in PERMANOVA (Permutational Multivariate Analysis of Variance). The PERMANOVA runs...
11. ### Unbalanced designs in PERMANOVA and Resampling Methods

Dear all, I am a new member and I have to say I am not sure if this is the right section for my question (I am working in ecology). I am dealing with unbalanced designs (I am comparing groups with different sample sizes) in PERMANOVA (Permutational Multivariate Analysis of Variance). The...
12. ### Bootstrap and hypothesis test

Hi, I have to decide whether two groups have the same variance or not. My sample size is less then impressive, 13 data points per group. I ran Bartletts test and got a p-value of 0.09 - but I suspected that the relatively high value might be due to the small sample size. So, I ran a...
13. ### Bootstrapping 0.632+ AUC with fixed test sets

Hi, I want to compare different binary classifiers in terms of their AUC values on test sets. I have data over one year with about 2000 observations each month. Now I would like to use the data in each of the last three months as separate test sets while using the months prior to a...
14. ### The bootstrap method for medical modelling

I am part of a team creating a model for paediatric hospitalised patients and would appreciate some help. We are looking to produce an accurate model for weight estimation, using input variables of gender, age and mid-upper arm circumference. This would be helpful as some children arrive in...
15. ### How to Fit polynomial regression by bootstrap and establishing IC of each parameters

#Hi everybody and excuse me for my bad english for this request on R. #here parameter of an hypothetical interval : x=c(60,59,55,49,43,38,33,28,24,20,17,15,12,10,8,6,5) y=c(59,55,49,43,38,33,28,24,20,17,15,12,10,8,6,5,4) #I adjusted it by a polynomial regression degree 3 (not the best...
16. ### Bootstrap procedure to test difference between correlation coefficients

Hi everyone, I have two correlation coefficients (r1 and r2), obtained within the same sample (20 subjects). My aim is to test it they are significantly different. r1 is the correlation between a neurophysiological parameter and a behavioural parameter in condition A; r2 is the correlation...
17. ### How to merge two data sets with varying date intervals?

I'm sure this problem isn't unique. I have two sets of data, both \$ values and I want to add them together and plot them on a chart. The problem is that one data set is quarterly and the other is daily but I want to display the resulting set (the addition of the two data sets) in weekly or...
18. ### Bootstrap strange estimate

Hello everyone, I'm a statistical novice, I would like your help. I'm analyzing non-normally distributed variables. To develop the confidence interval I preferred to use non-parametric method: bootstrap. Unfortunately I get output biased estimates and standard errors high, even though I used a...
19. ### Bootstrapping code help needed in r??

Hello friends. So I am ready to jump off a building because I cannot figure out this code for my LIFE. Everytime I run it, I get the standard error of 0 (bias=0 too) so obviously I'm doing something wrong because it's using the same sample when I want 1000 iterations. I want the AIC of the...
20. ### Inaccuracy of Non-Parametric Bootstrap for great sample sizes in Excel-VBA

My aim is to evaluate the performance of parametric and non-parametric Bootstrap under specific circumstances; and particularly their ability to capture the population mean within their produced confidence intervals -from now and on when talking about "coverage" I mean the ability of the...