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...example: this is, of course, OK: > data(kmenta) > demand <- q ~ p + d > instr <- ~ d + f > fit1 <- systemfit("2SLS", eqns=list(demand), inst=instr, data=kmenta) But, now if I'd like to estimate a model with logarithm of p as a regressor, an error occurs: > demand2 <- q ~ log(p) + d > fit2 <- systemfit("2SLS", eqns=list(demand2), inst=instr, data=kmenta) Error in log(p) : Object "p" not found However, estimating the same formula with OLS using the regular 'lm' is OK: > fit2.ols <- lm(demand2, kmenta) Transforming a...

...linear model isn't the "optimal" method, but I would like to make sure the parameter estimates and the se's are matching before I attempt more difficult problems. rm(list=ls(all=TRUE)) print( "running nlsystemfit models test at end...") data( kmenta ) attach( kmenta ) ##demand2 <- q ~ d0 + d1 * p + d2 * d supply2 <- q ~ s0 + s1 * p + s2 * f + s3 * a ##system2 <- list( demand2, supply2 ) ##labels <- list( "Demand", "Supply" ) ##inst <- ~ d + f + a ##sv2 <- c(d0=3,s2=2.123,d2=4,s0=-2.123,s3=4.234,d1=4.234,s1=0.234) sv2 <- c(s0=-2.123...

Hi, I have two products which are substitudes. I try to fix a system as below to mydata. Demand1 = A1 -B1*Price1 + C1*Price2 Demand2 = A2 +B2*Price1 - C2*Price2 I would expect C1 & B2 to be symmetric, If they are truly substitude. How can I enforce this symmetry when creating a system of equations via SystemFit ? -- View this message in context: http://www.nabble.com/SystemFit-tp24588252p24588252.html Sent from the R help...

...lhs[[i]] <- eval( formula( eqns[[i]] )[2] ) rhs[[i]] <- eval( formula( eqns[[i]] )[3] ) residi[[i]] <- lhs[[i]] - rhs[[i]] r <- rbind( r, as.matrix( residi[[i]] ) ) } ## blah, blah, blah.... knls <- obj } print( "calling nlstest" ) demand2 <- q ~ d0 + d1 * p + d2 * d supply2 <- q ~ s0 + s1 * p + s2 * f + s3 * a system2 <- list( demand2, supply2 ) sv2 <- c(d0=3,d2=4,d1=4.234,s0=-2.123,s2=2.123,s3=4.234,s1=0.234) ### call the nlm function to get the estimates... estnew <- nlm( knls, sv2, hessian=TRUE, print.level=1, eqn...

...lhs[[i]] <- eval( formula( eqns[[i]] )[2] ) rhs[[i]] <- eval( formula( eqns[[i]] )[3] ) residi[[i]] <- lhs[[i]] - rhs[[i]] r <- rbind( r, as.matrix( residi[[i]] ) ) } ## blah, blah, blah.... knls <- obj } print( "calling nlstest" ) demand2 <- q ~ d0 + d1 * p + d2 * d supply2 <- q ~ s0 + s1 * p + s2 * f + s3 * a system2 <- list( demand2, supply2 ) sv2 <- c(d0=3,d2=4,d1=4.234,s0=-2.123,s2=2.123,s3=4.234,s1=0.234) ### call the nlm function to get the estimates... estnew <- nlm( knls, sv2, hessian=TRUE, print.level=1, eqn...

Hi, I am trying to use method `validates_presence_of'' for validating my input fields on form . I m using it in my action class as follows:- ======================= validates_presence_of(params[:product][:quantity]) ====================== But when I am running my application i m getting error like:- ========================= undefined method `validates_presence_of'' for