Why is LaTeX failing to compile in RMarkdown - r

Question

My code should be a pretty easy knit to a pdf, but it will not compile and I'm getting this message in R Markdown:
! LaTeX Error: Unicode character ₁ (U+2081)
not set up for use with LaTeX.
Error: LaTeX failed to compile L-work-5.tex. See https://yihui.org/tinytex/r/#debugging for debugging tips. See L- work-5.log for more info.
Execution halted
here is the code:
---
title: "work 5"
author: "PLars"
date: "4/2/2022"
output: pdf_document
fonttheme: professionalfonts
fontsize: 12pt
editor_options:
markdown:
wrap: 72
---
```{r, echo = FALSE, results = "hide", message = FALSE, purl = FALSE}
library(knitr)
opts_chunk$set(tidy = FALSE,
fig.align = "left",
background = '#a6a6a6',
fig.width = 10,
fig.height = 10,
out.width ="\\linewidth",
out.height = "\\linewidth",
message = FALSE,
warning = FALSE,
fig.align = "left"
)
options(width = 55, digits = 3)
library(scales)
percent <- function(x, digits = 2, format = "f", ...) {
paste0(formatC(100 * x, format = format, digits = digits, ...), "%")
}
library(haven)
library(tinytex)
library(stargazer)
library(tidyverse)
library(texreg)
library(dplyr)
library(texreg)
library(AER)
library(tidyverse)
```
**Part I - Categorical Models (5 points)**
Say that you estimate an ordered logit model with a three category
dependent variable and two independent variables, X~₁i~ and X~₂i~, and
obtain the following results:
```{=tex}
\begin{center}
\begin{tabular}{c|rc}
\hline \hline
& $\hat{\beta}$ & SE \\
\hline
$X_{1}$ & $-0.68$ & $(0.23)$ \\
$X_{2}$ & $-0.47$ & $(0.13)$ \\
\hline
$\tau_1$ & $-1.02$ & $(0.46)$ \\
$\tau_2$ & $.85$ & $(0.21)$ \\
\hline
\end{tabular}
\end{center}
```
```{=tex}
\begin{enumerate}
\item Calculate $\Pr(Y_i=1 | X_{1i}=1, X_{2i}=0)$.
\item Calculate $\Pr(Y_i=2 | X_{1i}=1, X_{2i}=0)$.
\item Calculate $\Pr(Y_i=3 | X_{1i}=1, X_{2i}=0)$.
\item Calculate the first difference (difference in probability in category) that result from changing X_{2i} from -2 to 2, holding X_{1i} fixed at 0. Do calculations for each possible value of Y_i.
\item Explain how we might assess whether the parallel regression assumption holds for this model? If it does not, what alternative might you pursue if this were your model?
\end{enumerate}
```
#
First, we calculate $X_i \beta$
```{r}
(xiB <- (-.068*1) + (-0.47*0))
```
Then, plug into the following equations:
```{r}
(prob1 <- 1/(1 + exp(-(-1.02-xiB))))
(prob2 <- 1/(1 + exp(-(.85-xiB))) - prob1)
(prob3 <- 1 - (1/(1 + exp(-(.85-xiB)))))
prob1 + prob2 + prob3
```

Answer 1

For a start, try deleting the special characters ₁ and ₂ in the line
two independent variables, X~₁i~ and X~₂i~
This will let you compile.
You might be able to get this to work by including something like
\newunicodechar{₁}{\ensuremath{{}_1}}
and similarly for the subscript-2 character, at the top of your file (from this TeX Stack Exchange question), but I haven't tested it and don't want to go down that rabbit hole right now ...
Or just change the relevant text to
two independent variables, $X_{1i}$ and $X_{2i}$
which will probably typeset it as originally intended!