Linked Questions

1
vote
1answer
307 views

Get the new variance of the data [duplicate]

I got an initial mean $\mu_1$ and std $\sigma_1$ by sampling samples, these samples are generated by an unknown distribution and later I drop these samples. Then I sampled some samples and got the ...
1
vote
0answers
238 views

Getting a combined variance, given two variances [duplicate]

I'm getting two error variance values from two third-party sensors, and need to multiply these variances with the position state estimates of the target they're tracking. Once that's done, the ...
3
votes
0answers
141 views

How do I determine the variance of a collection of groups? [duplicate]

I’m trying to compute the variance of how much pumpkins weigh across pumpkins from 125 farms. However, I only have, for each farm, three pieces of data: (1) the variance of weights for pumpkins from ...
1
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0answers
38 views

How do I test whether means are equal when I have summary stats for 2 samples from one population and for 1 sample from a second? [duplicate]

I think this is a "meta-analysis" situation. I've got 3 samples (from 3 studies); I've assumed that two are from population A (treatment A) and one is from population B (treatment B). I have the ...
0
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0answers
32 views

Pooling variance of two samples with sample means and sample variance [duplicate]

I am new to this so I don't have enough reputation to comment on the original post here. I have a similar problem with equal weighting, and have n = m = 3. I believe this means I need to use sample ...
17
votes
6answers
28k views

What does pooled variance "actually" mean?

I am a noob in statistics, so could you guys please help me out here. My question is the following: What does pooled variance actually mean? When I look for a formula for pooled variance in the ...
1
vote
2answers
6k views

Combining results of two samples to find combined standard deviation

I was making an attempt to solve the following problem sets, however, my answer 15.913 seemed quite different from that in the answer key 16.84. I have checked my answer a few times and re-doing the ...
1
vote
1answer
2k views

Inverse-variance weighting

I'm writing a Bachelor Thesis in engineering an a small part of it has two deal with assigning weights to independent measurements. This is from the thesis: I am pretty sure that what equations (3.23)...
4
votes
1answer
1k views

How does one go about determining the standard deviation of an entire sample data set?

I have frequently been faced with analyzing csv files that are limited in length to approximately 32,000 records in length (overflows at 32,768, from signed integer limits on a 16 bit wide data bus). ...
3
votes
0answers
4k views

How to calculate 'weighted' pooled/composite statistics for two given groups given group statistics

I have two sets of independent samples from the same distribution. For each, I have calculated sample weighted mean (u1, u2) sample weighted std deviation (d1, d2) sample weighted std error (e1, e2) ...
1
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1answer
1k views

Aggregating standard deviation to a summary point

I have a range of data (server performance statistics) is formatted as follows, for each server: ...
2
votes
1answer
2k views

Proof to obtain pooled variance equation [closed]

I was checking the definition of pooled variance, and although I think it makes sense intuitively, I was wondering how can one obtain that estimator. For the case of only one group, I understand the ...
0
votes
1answer
2k views

Variance of subsample

Total sample = subsample 1 + subsample 2 I have the mean and variance of the total sample and subsample 1. I have n for total, subsample 1, and subsample 2. I can calculate the mean of subsample 2 ...
1
vote
0answers
578 views

Calculate variance of subpopulation given variance of overall population and its complement

I'd like to be able to calculate the sample variance for a subpopulation [B] given the sample mean and variance for its complement [A] and the overall population [A+B]. I have the sample mean and ...
0
votes
1answer
255 views

Average of values, their standard deviations and ranges

After reading for hours, I am still swimming. I have a set of plasma concentration results from different labs: ...

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