<p>There are a number of questions posted by new users asking how to interpret basic linear model output with interactions. An example from just now: <a href="https://stats.stackexchange.com/questions/418024/one-main-effect-is-positive-while-other-is-negative-but-interaction-effect-is-po">One main effect is positive while other is negative but interaction effect is positive in an interaction;Interpretation help</a>. </p>

<p>Do we have a canonical question &amp; answer that addresses these? If not, I can write one that explains this graphically. </p>
