# Tagged Questions

A weighted mean (or weighted average) is like an ordinary mean, but the observations don't contribute equally - more emphasis is placed on some data values than others; they are weighted by a bigger or smaller amount than 1/n.

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### calculating weighted CIs and interpretation

I have a weighted mean and I would like to calculate a weighted confidence interval and had a couple questions about interpretation. If one calculates the standard error of the weighted mean ...
187 views

### Alternate weighting schemes for random effects meta-analysis: missing standard deviations

I am working on a random effects meta-analysis covering a number of studies which do not report standard deviations; all studies do report sample size. I do not believe it is possible to approximate ...
400 views

### Compare Log-Normal Distributions

I am looking at distributions for the fuel consumption of vehicles in the US and I have two sets of data: Data Set 1 - This is a dataset for the fuel consumption of all vehicles made available for ...
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### Centroid of nearest-neighbours on a hypersphere as a method for applying crossover in genetic algorithms

I am currently building a genetic algorithm to tune n parameters where n will probably be in the range of ...
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### What should I expect biweight weighting values to be?

I am working on a project that involves taking the biweight sample variance of a velocity dataset. This is defined as $\sigma_{BI}^2 = N\dfrac{\sum_{|u_i|<1}(1-u_i^2)^4(v_i-\bar{v})}{D(D-1)}$ ...
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### How do I calculate a weighted standard deviation? In Excel?

So, I have a data set of percentages like so: ...
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### Weighted Variance, one more time

Unbiased weighted variance was already addressed here and elsewhere but there still seems to be a surprising amount of confusion. There appears to be a consensus toward the formula presented in the ...
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### What's the most accurate way to sum the standard deviation (or variance) and mean for two sets of data with different numbers of observations? [duplicate]

I was wondering what the correct way to do this is. So far I have a method of my own which I'm not sure is optimal. At the moment I am first calculating the new mean as a normalized weighted sum of ...
191 views

### How to solve this “probabilities and weighted probabilities” type of question?

I always get confused by "probabilities and weighted probabilities" type of questions as I can't differentiate between the two of them. Consider following example. Urn 1 contains 5 white balls and ...
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### Weighted mean / average where you reward the lowest value / cost / distance

Best I've several weather-station (200), placed across the country (508 municipalities). Now, I would like to prescribe the weather info, e.g. temperature, to each of the municipalities of that ...
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### Analytic Hierarchy Process (AHP) - factor weight score

As title mentioned, how to determine the 'scale of relative importance' point for factor weight score? Besides, I have read some example of ahp saying there are 1-9 point, 1-5 point (1,2,3,4,5) and ...
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### Constrained regression for binary dependent variable

I would like to discuss the methodology for the following case: I have a data for several patients over several years for 5 factors describing the health of a particular patient. Every factor ...
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### What does it mean to say that “the population mean is a single fixed number?”

I am trying to figure out what it means if a population mean value is fixed.
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### How to introduce a weighted percentage?

We wanted to know the knowledge of people about how to eat fruits. For this we provided a party and invited 1000 people. There were 3 kind of fruits on the tables. Banana, orange and melon. If ...
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### Weighted mean formula for two groups of unequal size

I am very confused with the weighted mean formula. Wikipedia lists the formula as $\bar{x} = \frac{\sum_{i=1}^{n} w_{i}x_{i}}{\sum_{i=1}^{n} w_{i}}$. The article also includes a basic numerical ...
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### P-values of weighted means and weighted standard deviations

I have a lot of data like this: control: 0/12 0/14 0/12 and case: 104/111 94/108 36/57 and when I use arithmetic means and unbiased sample variance, I get mean1 = 0.000000 mean2=0.816049 ...
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### Weighted median

I'd like to compute a median of measurements taken from a population with 3 subgroups, A, B, and C. I'd like to the median to be "weighted", in the sense that each of the groups should have equal ...
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### Calculating a cubic mean value which summarizes conditions with different probabilities

I am not sure how to calculate a 'typical' cubic mean load (CML, where L=load=force) given CML values for various conditions which have different probabilities of occurrence. The conditions are ...
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### Hypothesis test for 2 Weighted Means

I was trying to compare pairs of medical cost from several customized groups. The medical cost is adjusted by age and gender distribution in the sample. The resulting per member medical cost in each ...
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### How to get weighted summaries of survey responses in R

I am analysing survey data. Since my demographic categories are discrete I can summarise responses within demographics using prop.table. However, I would also like ...
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### Gradient of a sum of indicators

EDITED w.r.t. whuber's comment: Say I have a function $\mathbb R^n \rightarrow \mathbb R$: $$f(w_1,\ldots,w_n) = \frac{n^-\sum_{i\in I^-}w_ix_i}{n^+\sum_{i\in I^+}w_ix_i}$$ with fixed \$x_i\in\mathbb ...
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### Weighted median of a portfolio

I need to calculate weighted median return for a portfolio (using MATLAB). There is information available online: MATLAB Central/rates&weights and Excel/note 4+4+4+7+7/5 logic How would you ...
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### Comparing retention rates with differing sample sizes

I'm looking to compare the retention rate of people who attended an event and those who did not. The list of those who did not (70) is significantly larger than those who have (28). Here is an ...
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### Okay to use oneway ANOVA to compare these 3 group proportions from aggregated dataset?

My situation: I am assessing outcomes of a university course redesign. One of the goals of the redesign project was to increase successful course completion, as measured by a decrease in the course ...
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### Optimal weight for weighted average

I have some data points for which I do not have individual errors. My goal is to calculate the weighted average and I am looking for the "optimal weights" that can be used. I was thinking about the ...