How to get the confidence interval for bootstrap?

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Adnan Barkat
Adnan Barkat on 25 Nov 2021
Edited: Adam Danz on 28 Nov 2021
HI Everyone,
My data set consists of 185 columns and 53 rows. Each coloumn consists of integeres and NaN enteries. I need to delete only NaN enteries from each column and then run a bootstrap for each coloumn (I am not sure either I did this correctly or not please have a look on the script). However, I only get a single bootstrap value for each column. May someone sugget me how I can get upper and lower bounds for bootstrap.
clc
clear all
clc
u = readmatrix('R_0.01.csv');
s=u';
s=sort(s);
nBoot=2000;
for i=1:185
bb=s(:,i);
X = bb(~isnan(bb));
[bci(:,i),bmeans(:,i)] = bootci(nBoot,{@mean,X},'alpha',.1,'type','per');
bmu(i,1) = mean(bmeans(:,i));
end

Accepted Answer

Adam Danz
Adam Danz on 26 Nov 2021
Edited: Adam Danz on 28 Nov 2021
Why are you sorting s in s=sort(s)?
There's no need to manually eliminate the NaN values and there's no need to use a loop.
Here's a demo. bci is 2*n for n columns of s showing the [lower; upper] CIs.
u = rand(6,500) .* (1:6)';
s=u';
% s=sort(s);
nBoot=2000;
[bci,bmeans] = bootci(nBoot,{@(v)mean(v,'omitnan'),s},'alpha',.1,'type','per')
bci = 2×6
0.4915 0.9732 1.4090 1.9137 2.4013 2.9949 0.5350 1.0559 1.5363 2.0856 2.6109 3.2460
bmeans = 2000×6
0.5203 1.0467 1.4952 1.9917 2.4646 3.1421 0.5136 1.0534 1.4801 2.0494 2.5013 3.1802 0.5008 1.0113 1.4882 2.0149 2.5297 2.9563 0.5163 1.0236 1.5449 1.9367 2.5298 3.2134 0.5116 0.9381 1.4810 1.9140 2.4883 3.0335 0.5150 0.9864 1.5005 2.0132 2.5917 3.1490 0.5081 1.0345 1.4809 2.0112 2.4609 3.2744 0.5360 0.9740 1.4648 2.0291 2.5141 2.9913 0.4948 1.0058 1.4750 2.0584 2.5010 3.0882 0.5117 1.0126 1.4586 2.0869 2.5427 3.0350
bmu = mean(bmeans)
bmu = 1×6
0.5131 1.0148 1.4744 1.9976 2.5058 3.1196
Plot CIs to see if they make sense. The red lines within each boxplot show the median values. The light blue error bars are the CIs around the mean values.
clf()
boxplot(s)
hold on
errorbar(1:numel(bmu), bmu, bmu-bci(1,:), bmu-bci(2,:), 'LineStyle', 'none')

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