#statstab #506 The VIF Score. What is it Good For? Absolutely Nothing

Thoughts: Maybe we need to think more closely about what these metrics mean.

#diagnostics #assumptions #regression #vif #variance #variableselection #error #multicolinearity

https://journals.sagepub.com/doi/abs/10.1177/10944281231216381

07 - Beyond Confounders โ€” Causal Inference for the Brave and True

#statstab #490 Effect size for difference between variances / Levene's test

Thoughts: Always found it odd that we ignore heterogeneity for inference. We treat it like a "error".

#heterogeneity #welch #levene #variance #cvr #standarddeviation

https://stats.stackexchange.com/questions/173880/effect-size-for-difference-between-variances-levenes-test

Effect size for difference between variances / Levene's test

I have tested a hypothesis of equal variances (using Levene's test), and would like to report an effect size alongside the significance test. Unfortunately, I cannot seem to find any references to ...

Cross Validated

#statstab #489 On the performance of the Neyman Allocation with small pilots

Thoughts: If you know your treatment condition will have larger variance you can optimise your sample size.

#nhst #samplesize #neynan #heterogeneity #welch #variance #pilot #se

https://www.sciencedirect.com/science/article/pii/S0304407624001398

Chaos Edge: Spark Innovation - Reed Hastings and Patrick

#creativity #variance #chaos

http://financemetrics.scienceontheweb.net Maximising the value of a portfolio. Calculating #Variance, #CoVariance and portfolio Variance using the magic of Matrix Algebra. Calculations feature 5 ftse stocks, BP, Vodafone, UU.L, Tesco and Morrison. Detailed exposition leads one through x transpose multiplied b x. #MatrixAlgebra
FinancialAnalysis

Weighting an average to minimize variance

How would you allocate money to a set of independent assets with to minimize volatility if some assets are more volatile than others?

John D. Cook | Applied Mathematics Consulting

#statstab #393 Statistically Efficient Ways to Quantify Added Predictive Value of New Measurements [actual post]

Thoughts: #392 has the comments, but this is where the magic happens.

#modelselection #modelcomparison #variance #effectsize #tutorial

https://www.fharrell.com/post/addvalue/

Statistically Efficient Ways to Quantify Added Predictive Value of New Measurements โ€“ Statistical Thinking

Researchers have used contorted, inefficient, and arbitrary analyses to demonstrated added value in biomarkers, genes, and new lab measurements. Traditional statistical measures have always been up to the task, and are more powerful and more flexible. Itโ€™s time to revisit them, and to add a few slight twists to make them more helpful.

Statistical Thinking

In case anyone's keeping score, the idea that JFETs have hugely variable properties and that this problem cannot be - or at least has not been - fixed with different design or manufacturing practices, this batch showed it pretty clearly to me.

20 J113s, minus 1 fake, equals 19 devices. I measured the Vgs / pinch-off voltage and the Id / drain current in my test rig. The result?

6 very distinct bins with between 2 and 6 devices in each. Vgs overall varied from (-) 1.30 V to 2.11 V (variance is 38% of the larger value, or 62% of the smaller...), and Id from 5.7 mA to 12.8 mA, a spread of 125% (!) of the smaller value.

No wonder so many JFET circuits just don't work if you don't hand-match the devices.

#variance #variability #characteristics #measure #measurement #match #JFET #tolerance

A quotation from Nassim Nicholas Taleb

Donโ€™t cross a river if it is four feet deep on average.

Nassim Nicholas Taleb (b. 1960) Lebanese-American essayist, statistician, risk analyst, aphorist
The Black Swan, Part 2, ch. 10 โ€œThe Scandal of Predictionโ€ (2007)

Sourcing, notes: wist.info/taleb-nassim-nicholaโ€ฆ

#quote #quotes #quotation #qotd #blackswan #assumptions #average #danger #expectations #mean #variability #variance