FRM Part I · FRM Exam Part I · Machine Learning and Prediction
A LASSO regression with a single standardized predictor minimizes the sum of squared residuals plus lambda times the absolute value of the coefficient. When the penalty is increased from a very small value to a very large value, which outcome is most likely for the coefficient and the model?
The coefficient shrinks toward zero and eventually becomes exactly zero. A larger LASSO penalty makes the model simpler, which raises bias but lowers variance. The exact-zero outcome arises from the L1 penalty's kink at zero, unlike ridge, where coefficients approach but do not reach zero.
- AThe coefficient moves toward zero and eventually equals exactly zero, increasing bias while reducing varianceCorrect
- BThe coefficient grows larger in magnitude, reducing bias and increasing variance
- CThe coefficient stays unchanged because the penalty affects only the intercept
- DThe coefficient moves toward zero but never reaches it, as in ridge regression
Explanation
Raising lambda in LASSO increases the cost of nonzero coefficients. Because the L1 penalty has a kink at zero, the coefficient reaches exactly zero for large enough lambda. The model becomes simpler, with higher bias and lower variance. The last option describes ridge, not LASSO.
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