# Five simple formulas for all parametric statistics

### List of the five simple formulas that you need for parametric Statistics.

These are the five formula that you need in order to analyze your data at college as well as graduate school and post doc work. $$Mean \; formula \quad \bar{X} ={\sum{X} \over {n}}$$
$$Variance \; formula \quad s^2 ={\sum{({X}-{\bar{X})}}^2 \over {n-1}}$$
$$F \; ratio \; formula \quad F={{MS_{between}} \over {MS_{within}}}$$
$$Paired \; t-test \; formula \quad {t_{paired}}= {\bar{X}_D \over \sqrt {s^2 \over {n}}}$$
$$t-test \; formula \quad t= {{\bar{X_1}-{\bar{X_2}}} \over \sqrt{{s_1}^2 \over {n_1}}+\sqrt{{s_2}^2 \over {n_2}}}$$
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### why sometimes n and sometimes

why sometimes n and sometimes n-1?

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### Use n-1 when you are working

Use n-1 when you are working with samples, that is in analyzing data from experiments.

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unreal!

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### Yes yes simple easy

Yes yes simple easy

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### The many faces of variance

The many faces of variance

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