Nothing

```
if(require("psychotools")) {
data("MathExam14W", package = "psychotools")
## scale points achieved to [0, 100] percent
MathExam14W$tests <- 100 * MathExam14W$tests/26
MathExam14W$pcorrect <- 100 * MathExam14W$nsolved/13
## select variables to be used
MathExam <- MathExam14W[ , c("pcorrect", "group", "tests", "study",
"attempt", "semester", "gender")]
## compute base model
bmod_math <- lm(pcorrect ~ group, data = MathExam)
lm_plot(bmod_math, densest = TRUE)
## compute tree
(tr_math <- pmtree(bmod_math, control = ctree_control(maxdepth = 2)))
plot(tr_math, terminal_panel = node_pmterminal(tr_math, plotfun = lm_plot,
confint = FALSE))
plot(tr_math, terminal_panel = node_pmterminal(tr_math, plotfun = lm_plot,
densest = TRUE,
confint = TRUE))
## predict
newdat <- MathExam[1:5, ]
# terminal nodes
(nodes <- predict(tr_math, type = "node", newdata = newdat))
# response
(pr <- predict(tr_math, type = "pass", newdata = newdat))
# response including confidence intervals, see ?predict.lm
(pr1 <- predict(tr_math, type = "pass", newdata = newdat,
predict_args = list(interval = "confidence")))
}
```

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