Statistics Topics
Plain-language companions to the interactive z table — the concepts behind the numbers, one page each.
Z-Score
Formula, interpretation, worked examples
Normal Distribution
The bell curve and the 68-95-99.7 rule
Z-Test
When to use it and how it works
P-Value
What it means - and what it doesn’t
Confidence Interval
Where 1.96 comes from
Variance vs Standard Deviation
The units difference, plainly
Sample vs Population SD
The N vs n-1 trap
Null Hypothesis
Rejection logic and error types
Degrees of Freedom
An intuitive explanation
Skewed Distributions
Left vs right skew, real examples
Z-Scores in Excel
Formula-by-formula how-to
Altman Z-Score
The bankruptcy formula (finance)