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# Correlation: still a magical number

Why is r always between 1 and -1? I get that it has to be, because r^2 is a proportion, but that is not coming at it from the angle I want to come at it from đź™‚ I want to know if there’s an intuitive link somewhere in why n – 1 is the…

# Confidence: still don’t get it

95% of the bars contain the true mean. Somehow, that does not mean that for any given bar, there is a 95% probability that it contains the true mean. Why doesnâ€™t it mean this? If it did mean this, then (it seems to me) you could say â€śThere is a 95% probability that the true…

# Statistics: n – 1

In the formula for the standard deviation,Â you divide by n – 1. A sore point for many of us. Just because it’s a bit more intuitive, let’s put the standard deviation aside and look at the mean deviation*, which is the average of the absolute deviations (as opposed to the average of the squared deviations).…

# Variation differs across levels â€“ MLwiN software for multilevel modelling

Students in classesÂ are more similar to each other than students in different classes. Students in schools are more similar to each other than students in different schools. This hierarchical fact of life â€“students are in classesÂ and classesÂ are in schools â€“ must be taken into consideration when doing statistical analysis, and it is typically done using…