iagnosis of cancer) --&gt;
&lt;!--   1. True negative (*e.g.*, correct diagnosis of "no cancer") --&gt;

---
name: mse
## Most common: MSE

.attn[Mean squared error (MSE)] is the most common loss function in a regression setting. (Not necessarily the best.)

`$$\text{MSE} = \dfrac{1}{n} \sum_{i=1}^n \left[ \color{#FFA500}{y}_i - \hat{\color{#20B2AA}{f}}(\color{#6A5ACD}{x}_i) \right]^2$$`

Note:

1. MSE is small when .hi-slate[prediction error] is small.
1. MSE .hi-slate[penalizes] big errors more than small