Model functions

at() function

at(f,n) or @(f,n)
defines a binary variable which is 1 if the factor f has level n for the record. For example, to fit a row factor only for site 3, use the expression at(site,3).row.

at(f,m,n) or @(f,m,n)
at(f,n) is extended so that at(f,i).X at(f,j).X at(f,k).X can be written as at(f,i,j,k).X provided at(f,i,j,k) is written as the first component of the interaction. Any number of levels may be listed.

at(f) or @(f)
at(f,i) is extended so that at(f) generates at(f,i) for all levels of f. Since this command is interpreted before the data is read, it is necessary to declare the number of levels correctly in the field definition. This extended form may only be used as the first term in an interaction.

le(f,n)
defines a binary variable which is 1 if the factor f has level lt= n for the record.

lt(f,n)
defines a binary variable which is 1 if the factor f has level lt n for the record.

ge(f,n)
defines a binary variable which is 1 if the factor f has level gt= n for the record.

le(f,n)
defines a binary variable which is 1 if the factor f has level gt n for the record.

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