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Simple explanation of Covariates
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Covariates
Conceptual explanation & demonstration
Imagine you want to know the effect of gender on hand writing neatness scores.
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.
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?
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?
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?
Let’s look at the data set
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
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
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
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
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
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.
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,
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.
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).
