LaTeX 的 R Markdown 错误 - 显然不是 $ $ 问题

Question

下面的第二部分代码写在 Markdown 部分，而第一部分代码生成 R 调用的对象。例如，我将设置

homoscedastic_variance = 1
heterokesdastic_variance = 1

$$Var_{homo}(\hat{\tau}) = \frac{1}{N_tN_c}\sum_{i=1}^N (Y_i - \bar{Y}) = `r homoscedastic_variance`$$

While the heteroskedastic is estimated as:

$$Var_{hetero}(\hat{\tau}) = \frac{1}{N_t} s_t^2 + \frac{1}{N_c}s_c^2 = `r heterokesdastic_variance`$$

with $s_c = \frac{1}{N_c - 1}\sum_{i: W_i = 0} (Y_i - \bar{Y_c})^2 $ and analogously for $s_t$.

Then, we can make two confidence intervals:

$CI_{homo} = [`r treatment_effect` \pm 1.96*sqrt(`r homoscedastic_variance`)]$

$CI_{hetero} = [`r treatment_effect` \pm 1.96*sqrt(`r heterokesdastic_variance`)]$

使用 knit -> PDF 选项时，我收到此错误：

! Missing $ inserted.
<inserted text> 
                $
l.108 with \$s\_c = \frac{1}{N_c - 1}
                                     \sum\_\{i: W\_i = 0\} (Y\_i - 

Try to find the following text in script_ps1.Rmd:
  with \$s\_c = \frac{1}{N_c - 1} 

You may need to add $ $ around a certain inline R expression `r ` in script_ps1.Rmd (see the above hint). 

See https://github.com/rstudio/rmarkdown/issues/385 for more info.
Erro: LaTeX failed to compile script_ps1.tex. See https://yihui.org/tinytex/r/#debugging for debugging tips. See script_ps1.log for more info." 

我在 LaTeX 中试过这个，它编译得很好；任何人都知道为什么我得到这个错误？我觉得有趣的是它建议使用 $ $ 内联 R 表达式，但该错误与具有任何内联 R 表达式的表达式无关（如果我删除“with $s_c ...”部分，编织就可以了！

Answer 1

这里去掉末尾的空格：

$s_c = \frac{1}{N_c - 1}\sum_{i: W_i = 0} (Y_i - \bar{Y_c})^2 $

即

$s_c = \frac{1}{N_c - 1}\sum_{i: W_i = 0} (Y_i - \bar{Y_c})^2$

这行得通。