Test for conditional independence in a dataframe
Test for conditional independence in a dataframe.
ciTest_df(x, set = NULL, ...)
x |
A dataframe. |
set |
A specification of the test to be made. The tests are of
the form u and v are independent condionally on S where u and v
are variables and S is a set of variables. See 'details' for
details about specification of |
... |
Additional arguments. |
set can be 1) a vector or 2) a right-hand sided formula in which
variables are separated by '+'. In either case, it is tested if the first
two variables in the set are conditionally independent given the
remaining variables in set. (Notice an abuse of the '+' operator in
the right-hand sided formula: The order of the variables does matter.)
If set is NULL then it is tested whether the first two
variables are conditionally independent given the remaining variables.
If set consists only of factors then x[,set] is converted to a
contingency table and the test is made in this table using
ciTest_table().
If set consists only of numeric values and integers then
x[,set] is converted to a list with components cov and
n.obs by calling cov.wt(x[,set], method='ML'). This list is
then passed on to ciTest_mvn() which makes the test.
An object of class citest (which is a list).
Søren Højsgaard, sorenh@math.aau.dk
data(milkcomp1) ciTest(milkcomp1, set=~tre + fat + pro) ciTest_df(milkcomp1, set=~tre + fat + pro)
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