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JMP Pro 11 Canonical plot

andreas_scherer

Community Trekker

Joined:

Jan 18, 2015

In JMP Pro 11 I am performing a Linear Discriminant analysis with two categories, each consisting of 26 observations. In the canonical plot, the 50% normal contour ellipsoids should frame 13 observations, but they only frame 5 and 6. Would anybody know why this would be the case?

Screen Shot 2017-02-24 at 22.18.35.png

 

 

 

 

1 ACCEPTED SOLUTION

Accepted Solutions
Dan_Obermiller

Joined:

Apr 3, 2013

Solution

From the JMP Help:

"The option Show Normal 50% Contours shows areas that contain roughly 50% of the points for that group if the assumptions are correct. Under linear discriminant analysis, they are all the same size and shape."

 

My additions: 

Assumptions: a normal distribution with common covariance for the two groups.

 

Remember that the ellipse is an ESTIMATE based on the model. It is not a guarantee of having 50% of the observations within the ellipse.

Dan Obermiller
1 REPLY
Dan_Obermiller

Joined:

Apr 3, 2013

Solution

From the JMP Help:

"The option Show Normal 50% Contours shows areas that contain roughly 50% of the points for that group if the assumptions are correct. Under linear discriminant analysis, they are all the same size and shape."

 

My additions: 

Assumptions: a normal distribution with common covariance for the two groups.

 

Remember that the ellipse is an ESTIMATE based on the model. It is not a guarantee of having 50% of the observations within the ellipse.

Dan Obermiller