Simple explanation of Covariates

1. Covariates
Conceptual explanation &
demonstration

2. Imagine you want to know the effect of gender on hand
writing neatness scores.

3. Imagine you want to know the effect of gender on hand
writing neatness scores.
And you find that females tend to get higher
handwriting neatness scores.

4. Imagine you want to know the effect of gender on hand
writing neatness scores.
And you find that females tend to get higher
handwriting neatness scores.
But then you ask yourself. What if age were added to
the mix?

5. Imagine you want to know the effect of gender on hand
writing neatness scores.
And you find that females tend to get higher
handwriting neatness scores.
But then you ask yourself. What if age were added to
the mix?
Does the age of the male or the female have an effect?

6. Imagine you want to know the effect of gender on hand
writing neatness scores.
And you find that females tend to get higher
handwriting neatness scores.
But then you ask yourself. What if age were added to
the mix?
Does the age of the male or the female have an effect?
Is there a way to see what the difference would be if
we eliminated the age effect?

7. Let’s look at the data set

8. Participant Gender Hand Writing
Neatness Scores
Bubba Male 5
Boston Male 4
Camille Female 6
Cassidy Female 7
Delbert Male 6
Danny Male 5
Ester Female 8
Emily Female 9

9. Participant Gender Hand Writing
Neatness Scores
Bubba Male 5
Boston Male 4
Camille Female 6
Cassidy Female 7
Delbert Male 6
Danny Male 5
Ester Female 8
Emily Female 9
It appears that
females have
higher scores

10. Participant Gender Hand Writing
Neatness Scores
Bubba Male 5
Boston Male 4
Camille Female 6
Cassidy Female 7
Delbert Male 6
Danny Male 5
Ester Female 8
Emily Female 9
It appears that
females have
higher scores
than
males

11. Participant Gender Hand Writing
Neatness Scores
Bubba Male 5
Boston Male 4
Camille Female 6
Cassidy Female 7
Delbert Male 6
Danny Male 5
Ester Female 8
Emily Female 9
Now let’s add age

12. Participant Gender Age Hand Writing
Neatness Scores
Bubba Male Older 5
Boston Male Younger 4
Camille Female Older 6
Cassidy Female Younger 7
Delbert Male Older 6
Danny Male Younger 5
Ester Female Older 8
Emily Female Younger 9

13. Participant Gender Age Hand Writing
Neatness Scores
Bubba Male Older 5
Boston Male Younger 4
Camille Female Older 6
Cassidy Female Younger 7
Delbert Male Older 6
Danny Male Younger 5
Ester Female Older 8
Emily Female Younger 9
There is a way
statistically to control
for or take out the
effect of age and then
see if gender still has
an effect.

14. Participant Gender Age Hand Writing
Neatness Scores
Bubba Male Older 5
Boston Male Younger 4
Camille Female Older 6
Cassidy Female Younger 7
Delbert Male Older 6
Danny Male Younger 5
Ester Female Older 8
Emily Female Younger 9
If gender does not
have an effect after
controlling for age,

15. Participant Gender Age Hand Writing
Neatness Scores
Bubba Male Older 5
Boston Male Younger 4
Camille Female Older 6
Cassidy Female Younger 7
Delbert Male Older 6
Danny Male Younger 5
Ester Female Older 8
Emily Female Younger 9
. . . then we would say
that age was probably
the real factor
differentiating
handwriting neatness.

16. In summary, a covariate (age) is used to determine how
much another factor (gender) is really having an effect
on a dependent variable (handwriting neatness
scores).