# One Treated Unit That Becomes Untreated

Suppose I have a set of units $$n_i, i = 1,...,N$$. One unit was receiving a treatment $$n_j = 1$$ at times $$t=1$$ to $$t=\tau$$. All other units never received the treatment so $$\forall t, n_i=0,i\neq j$$. At $$\tau+1$$ to $$T=t,T>>\tau+1$$, $$n_j=0$$.

Suppose the shock to $$n_j$$ is totally exogenous for simplicity.

Is there a causal framework that allows me to estimate the impact of $$n_j=1$$?