# Statistics/Summary, Study Guide and Formulas

A Statistic ${\displaystyle {\hat {\Theta }}}$
Unbiased estimator ${\displaystyle \mu _{\hat {\Theta }}{=}E({\hat {\Theta }}){=}\theta }$ of parameter ${\displaystyle \theta }$
sample size confidence that error less than e when sample size is ${\displaystyle n{=}({z_{\alpha /2}\sigma \over e})^{2}}$
confidance interval ${\displaystyle {\bar {x}}-z_{\alpha /2}{\sigma \over {\sqrt {n}}}<\mu <{\bar {x}}+z_{\alpha /2}{\sigma \over {\sqrt {n}}}}$