Inferential Statistics (Leaving Cert Mathematics): Flashcards

Large group being studied in research

Smaller group studied to represent population

Around 1000 people

$\hat{p}$, fraction in sample with characteristic

$p$, true fraction in population with characteristic

$E = \frac{1}{\sqrt{n}}$

How much sample result might differ from true population value

Margin of error decreases

$\hat{p} \pm \frac{1}{\sqrt{n}}$

Method works correctly 95% of the time

$\hat{p} - E$ or $\hat{p} - \frac{1}{\sqrt{n}}$

$\hat{p} + E$ or $\hat{p} + \frac{1}{\sqrt{n}}$

$n = (\frac{1}{E})^2$ or $n = \frac{1}{E^2}$

Quadruple (multiply by 4)