Num8ers statistics reference
Complete K-12 Statistics Formula Guide
Search 450 statistics formulas across data basics, probability, distributions, sampling, confidence intervals, hypothesis testing, correlation, regression, time series, business statistics, and AP or IB extensions.
How to use this statistics guide
Search by formula, variable, or topic.
Filter by a category pill.
Read the expression, definition, and variables.
Use the mini calculator for common formulas.
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Statistics Formula FAQs
Does this K-12 statistics formula page include all 450 formulas?
Yes. It includes all 450 formulas from the uploaded K-12 statistics checklist, grouped by category with formulas, definitions, and variable explanations.
How should students use this statistics formula guide?
Search for a topic or formula, read the definition and variables, then match the symbols to the data in the problem.
What is the mean formula?
The mean is x-bar = sum of data values divided by n.
What is the median?
The median is the middle value after data are ordered.
What is the mode?
The mode is the value that occurs most often.
What is the range formula?
Range is maximum value minus minimum value.
What is the interquartile range?
IQR = Q3 - Q1, measuring the spread of the middle 50 percent of data.
What is the standard deviation formula used for?
Standard deviation measures typical distance from the mean.
What is a z-score?
A z-score is z = (x - mean) / standard deviation.
What is the probability formula?
Probability is favorable outcomes divided by total outcomes.
What is conditional probability?
Conditional probability is P(A|B) = P(A and B) / P(B).
What is the addition rule of probability?
P(A or B) = P(A) + P(B) - P(A and B).
What is the multiplication rule of probability?
P(A and B) = P(A)P(B|A).
What is a combination formula?
Combinations are nCr = n! / (r!(n-r)!).
What is a permutation formula?
Permutations are nPr = n! / (n-r)!.
What is binomial probability?
Binomial probability is C(n,k)p^k(1-p)^(n-k).
What is a confidence interval?
A confidence interval is estimate plus or minus a critical value times standard error.
What is a p-value?
A p-value is the probability of getting a result at least as extreme as observed if the null hypothesis is true.
What is correlation?
Correlation measures the direction and strength of a relationship between two quantitative variables.
What is a regression line?
A regression line predicts y from x using an equation like y-hat = a + bx.