k whether including or excluding the covariate <code>C</code> in the model reveals any connection between X and Y.</p>
<p>In each of the three cases, the direct causal link between X and Y will have an X multiplier of <span class="math inline">\(-1\)</span>. This makes it easy to check whether the model coefficient on X is correct or whether the backdoor pathway interferes with seeing the direct X <span class="math inline">\(\rightarrow\)</span> Y pathway.</p>
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