Margins and MCP commands produce the different results.

[April Kimm]

I am trying to calculate predicted values but the margins command and mcp command produce the different values. For example, according to the margins command, when control=1, the predicted value is 0.0035953 but according to the mcp graph, it is over 0.04. Also, when control=6, the margins command produces 0.0075143 while the mcp graph indicates over 0.008.

I used the following commands.

margins, at ( control = (1 (1) 6)) atmeans expression(invlogit(predict(xb)))
mcp control , margopts(expression(invlogit(predict(xb))))

Could anyone explain what is going on? Thank you!

[Andrew Musau]

marginscontplot is from the Stata Journal, as you are asked to explain in FAQ Advice #12.

Margins and MCP commands produce the different results

That cannot be correct because mcp calls on margins to do the calculations. To see the equivalent margins command, use the option -showmarginscmd-

mcp control , margopts(expression(invlogit(predict(xb)))) showmarginscmd

[Richard Williams]

What is the estimation command before margins?

mcp does not default to atmeans. Drop it from the margins command and see what happens.