Null hypothesis for point biserial

Null-hypothesis for a Point Biserial

Conceptual Explanation

With hypothesis testing we are setting up a null-hypothesis –

With hypothesis testing we are setting up a null-hypothesis – the probability that there is no effect or relationship –

With hypothesis testing we are setting up a null-hypothesis – the probability that there is no effect or relationship – and then we collect evidence that leads us to either accept or reject that null hypothesis.

As you may recall, a Point-Biserial Correlation is a value that makes it possible to statistically test the relationship between a dichotomous variable and a continuous variable.


Person

Depressed

1 = not depressed

2 = depressed

Amount of Shame

A 1 10

B 1 9

C 1 10

D 2 2

E 2 2


Person

Depressed

1 = not depressed

2 = depressed

Amount of Shame

A 1 10

B 1 9

C 1 10

D 2 2

E 2 2

either / or


Person

Depressed

1 = not depressed

2 = depressed

Amount of Shame

A 1 10

B 1 9

C 1 10

D 2 2

E 2 2


Person

Depressed

1 = not depressed

2 = depressed

Amount of Shame

A 1 10

B 1 9

C 1 10

D 2 2

E 2 2

takes on many values

Here is a template for writing a null-hypothesis for a Point-Biserial Correlation:

Here is a template for writing a null-hypothesis for a Phi-Coefficient:

There is no statistically significant relationship between the [insert variable] and [insert variable].

Example 1

A researcher wishes to determine if a significant relationship exists between height and college graduation status (1 = graduated; 2 = not graduated).

Problem

A researcher wishes to determine if a significant relationship exists between height and college graduation status.

Template for a Phi-Coefficient Null-Hypothesis

There is no statistically significant relationship between the [insert independent variable] and [insert dependent variable].

Null-hypothesis for this Problem


Problem






Problem






d

Problem






s

Problem





There is no statistically significant relationship between the student height and [insert variable].

s

Problem





There is no statistically significant relationship between the student height and college graduation status.

s


There is no statistically significant relationship between the student height and college graduation status.

Example 2

A researcher wishes to determine if a significant relationship exists between head circumference and political affiliation (Democrat vs. Republican).


vs.

vs.

Problem






Problem






s

Problem





There is no statistically significant relationship between the head circumference and [insert variable].

s

Problem





There is no statistically significant relationship between the head circumference and political affiliation.

s


There is no statistically significant relationship between the head circumference and political affiliation.

Null hypothesis for point biserial

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