statistic

[benny]

Hi,
Would like you to tell why we must use 30 samples as a minimal number of
sample for statistical analysis.

txs

 

[Harlan Grove]

Would like you to tell why we must use 30 samples as a minimal number of
sample for statistical analysis.

You don't necessarily. 30 is a rule-of-thumb based on normality assumption
and a particular significance level. However, rather off-topic. If you want
to learn basic statistics, buy & read a statistics text book.