Question

For these discussion questions:

Define Type I and Type II error and explain their importance in statistical research (5 points).

Discuss the use of directional and non-directional hypotheses. How do we make the decision to use directional or non-directional tests? (5 points)

Answer 1

Type 1 Error :

A Type 1 error , is the incorrect rejection of a true null hypothesis. The alpha symbol, is usually used to denote a Type I error

P(reject Ho /when it is true) =

Example:

Though the null hypothesis is true but we reject it ,it causes or leads to Type 1 error...

suppose we define

Ho: There is an equal performance (no difference) in a test conducted between boys and girls.

H1: There is an unequal performance ( a difference) in a test conducted between boys and girls.

Type2 Error :

A Type II error (sometimes called a Type 2 error) is the failure to reject a false null hypothesis. The probability of a type II error is denoted by the symbol  .

P(accept Ho/ when it is false) =

when we accept the alternative hypothesis when it is actually false it is referred as Type2 Error.

It is actually referred as power of the test.(1-)

Directional Hypothesis:

It is the hypothesis which expained the directional relationship between dependent and independent variable.

Example:

There is a high impact of sales when there is is high advertisement,

Non Directional Hypothesis:

It is the hypothesis which does not expained the directional relationship between dependent and independent variable.

example:

Relationship between age and job satisfaction.