We want to test

if the population mean of Group A is smaller than an expectation or the

population mean of Group B

Population std/var is given, sample std/var is

NOT given

Samples are drawn from two separate groups

All samples are drawn from a single group

We want to test if the population mean of Group

A is similar/close to an expectation or the population mean of Group B

Population std/var is NOT given, sample std/var

is given

Population std/var is NOT given, sample std/var

is calculated

Experiment condition is changed during data

measurement

We want to test if the population mean of Group

A is larger than an expectation or the population mean of Group B

Population std/var is given, sample std/var is

given

Experiment condition is unchanged during data

measurement