Get coefficients estimated by maximum likelihood into a stargazer table
Stargazer produces very nice latex tables for lm (and other) objects. Suppose I've fit a model by maximum likelihood. I'd like stargazer to produce a lm-like table for my estimates. How can I do this?
Although it's a bit hacky, one way might be to create a "fake" lm object containing my estimates -- I think this would work as long as summary(my.fake.lm.object) works. Is that easily doable?
An example:
library(stargazer)
N <- 200
df <- data.frame(x=runif(N, 0, 50))
df$y <- 10 + 2 * df$x + 4 * rt(N, 4) # True params
plot(df$x, df$y)
model1 <- lm(y ~ x, data=df)
stargazer(model1, title="A Model") # I'd like to produce a similar table for the model below
ll <- function(params) {
## Log likelihood for y ~ x + student's t errors
params <- as.list(params)
return(sum(dt((df$y - params$const - params$beta*df$x) / params$scale, df=params$degrees.freedom, log=TRUE) -
log(params$scale)))
}
model2 <- optim(par=c(const=5, beta=1, scale=3, degrees.freedom=5), lower=c(-Inf, -Inf, 0.1, 0.1),
fn=ll, method="L-BFGS-B", control=list(fnscale=-1), hessian=TRUE)
model2.coefs <- data.frame(coefficient=names(model2$par), value=as.numeric(model2$par),
se=as.numeric(sqrt(diag(solve(-model2$hessian)))))
stargazer(model2.coefs, title="Another Model", summary=FALSE) # Works, but how can I mimic what stargazer does with lm objects?
To be more precise: with lm objects, stargazer nicely prints the dependent variable at the top of the table, includes SEs in parentheses below the corresponding estimates, and has the R^2 and number of observations at the bottom of the table. Is there a(n easy) way to obtain the same behavior with a "custom" model estimated by maximum likelihood, as above?
Here are my feeble attempts at dressing up my optim output as a lm object:
model2.lm <- list() # Mimic an lm object
class(model2.lm) <- c(class(model2.lm), "lm")
model2.lm$rank <- model1$rank # Problematic?
model2.lm$coefficients <- model2$par
names(model2.lm$coefficients)[1:2] <- names(model1$coefficients)
model2.lm$fitted.values <- model2$par["const"] + model2$par["beta"]*df$x
model2.lm$residuals <- df$y - model2.lm$fitted.values
model2.lm$model <- df
model2.lm$terms <- model1$terms # Problematic?
summary(model2.lm) # Not working
Solution 1:
I was just having this problem and overcame this through the use of the coef
se
, and omit
functions within stargazer... e.g.
stargazer(regressions, ...
coef = list(... list of coefs...),
se = list(... list of standard errors...),
omit = c(sequence),
covariate.labels = c("new names"),
dep.var.labels.include = FALSE,
notes.append=FALSE), file="")
Solution 2:
You need to first instantiate a dummy lm
object, then dress it up:
#...
model2.lm = lm(y ~ ., data.frame(y=runif(5), beta=runif(5), scale=runif(5), degrees.freedom=runif(5)))
model2.lm$coefficients <- model2$par
model2.lm$fitted.values <- model2$par["const"] + model2$par["beta"]*df$x
model2.lm$residuals <- df$y - model2.lm$fitted.values
stargazer(model2.lm, se = list(model2.coefs$se), summary=FALSE, type='text')
# ===============================================
# Dependent variable:
# ---------------------------
# y
# -----------------------------------------------
# const 10.127***
# (0.680)
#
# beta 1.995***
# (0.024)
#
# scale 3.836***
# (0.393)
#
# degrees.freedom 3.682***
# (1.187)
#
# -----------------------------------------------
# Observations 200
# R2 0.965
# Adjusted R2 0.858
# Residual Std. Error 75.581 (df = 1)
# F Statistic 9.076 (df = 3; 1)
# ===============================================
# Note: *p<0.1; **p<0.05; ***p<0.01
(and then of course make sure the remaining summary stats are correct)