update exercises week 38

doc/LectureNotes/_build/html/_sources/exercisesweek38.ipynb

@@ -178,20 +178,12 @@
     "We see that $\\mathbb{E} \\big[ \\hat{\\boldsymbol{\\beta}}^{\\mathrm{Ridge}} \\big] \\not= \\mathbb{E} \\big[\\hat{\\boldsymbol{\\beta}}^{\\mathrm{OLS}}\\big ]$ for any $\\lambda > 0$.\n"
    ]
   },
-  {
-   "cell_type": "markdown",
-   "id": "65f6f914",
-   "metadata": {},
-   "source": [
-    "**b)** Why do we say that Ridge regression gives a biased estimate? Is this a problem?\n"
-   ]
-  },
   {
    "cell_type": "markdown",
    "id": "b4e721fc",
    "metadata": {},
    "source": [
-    "**c)** Show that the variance is\n"
+    "**b)** Show that the variance is\n"
    ]
   },
   {
@@ -297,7 +289,8 @@
    "source": [
     "$$\n",
     "\\mathrm{var}[\\tilde{y}]=\\mathbb{E}\\left[\\left(\\tilde{\\boldsymbol{y}}-\\mathbb{E}\\left[\\boldsymbol{\\tilde{y}}\\right]\\right)^2\\right]=\\frac{1}{n}\\sum_i(\\tilde{y}_i-\\mathbb{E}\\left[\\boldsymbol{\\tilde{y}}\\right])^2.\n",
-    "$$\n"
+    "$$\n",
+    "In order to arrive at the equation for the bias, we have to approximate the unknown function $f$ with the output/target values $y$."
    ]
   },
   {