remove broken equation tag

hypothesistesting/hypothesistesting.Rmd

@@ -234,10 +234,10 @@ can link the unobserved counterfactual outcomes to an observed outcome ($Y_i$)
 using treatment assignment ($Z_i$) like so:
 
 \begin{equation}
-Y_i = Z_i y_{i,1} + (1 - Z_i) y_{i,0} (\#eq:identity)
+Y_i = Z_i y_{i,1} + (1 - Z_i) y_{i,0}
 \end{equation}
 
-\@ref(eq:identity) says that our observed outcome, $Y_i$ (here, amount of
+The above equation says that our observed outcome, $Y_i$ (here, amount of
 taxes paid by person $i$), is $y_{i,1}$ when the person is assigned to the
 treatment group ($Z_i=1$), and $y_{i,0}$ when the person is assigned to the
 control group.
@@ -248,9 +248,8 @@ payments of every single person such that  $H_0: y_{i,1} = y_{i,0} + \tau_i$ whe
 $\tau_i=5$ for all $i$.
 
 Let us entertain this model for the sake of argument. What would this
-hypothesis imply for what we observe? We have the equation relating observed
-to unobserved in \@ref(eq:identity) so, this model or hypothesis would
-imply that:
+hypothesis imply for what we observe? The above equation relates observed
+to unobserved so, this model or hypothesis would imply that:
 
 $$ \begin{aligned}  Y_i & = Z_i ( y_{i,0} + \tau_i ) + ( 1 - Z_i) y_{i,0} \\
 & = Z_i  y_{i,0} + Z_i \tau_i + y_{i,0} - Z_i y_{i,0} \\