{
"cells": [
{
"cell_type": "markdown",
"metadata": {
"hide": true
},
"source": [
"# Noisy Learning\n",
"\n",
"##### Keywords: empirical risk minimization, bias, sampling distribution, hypothesis space, training error, out-of-sample error, variance, stochastic noise, bias-variance tradeoff"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Contents\n",
"{:.no_toc}\n",
"* \n",
"{: toc}"
]
},
{
"cell_type": "code",
"execution_count": 26,
"metadata": {
"hide": true
},
"outputs": [],
"source": [
"%matplotlib inline\n",
"import numpy as np\n",
"import scipy as sp\n",
"import matplotlib as mpl\n",
"import matplotlib.cm as cm\n",
"import matplotlib.pyplot as plt\n",
"import pandas as pd\n",
"pd.set_option('display.width', 500)\n",
"pd.set_option('display.max_columns', 100)\n",
"pd.set_option('display.notebook_repr_html', True)\n",
"import seaborn as sns\n",
"sns.set_style(\"whitegrid\")\n",
"sns.set_context(\"poster\")"
]
},
{
"cell_type": "code",
"execution_count": 27,
"metadata": {
"hide": true
},
"outputs": [],
"source": [
"def make_simple_plot():\n",
" fig, axes=plt.subplots(figsize=(12,5), nrows=1, ncols=2);\n",
" axes[0].set_ylabel(\"$y$\")\n",
" axes[0].set_xlabel(\"$x$\")\n",
" axes[1].set_xlabel(\"$x$\")\n",
" axes[1].set_yticklabels([])\n",
" axes[0].set_ylim([-2,2])\n",
" axes[1].set_ylim([-2,2])\n",
" plt.tight_layout();\n",
" return axes\n",
"def make_plot():\n",
" fig, axes=plt.subplots(figsize=(20,8), nrows=1, ncols=2);\n",
" axes[0].set_ylabel(\"$p_R$\")\n",
" axes[0].set_xlabel(\"$x$\")\n",
" axes[1].set_xlabel(\"$x$\")\n",
" axes[1].set_yticklabels([])\n",
" axes[0].set_ylim([0,1])\n",
" axes[1].set_ylim([0,1])\n",
" axes[0].set_xlim([0,1])\n",
" axes[1].set_xlim([0,1])\n",
" plt.tight_layout();\n",
" return axes"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Revisiting our model"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"Let us revisit our model from noiseless_learning.\n",
"\n",
"Let $x$ be the fraction of religious people in a county and $y$ be the probability of voting for Romney as a function of $x$. In other words $y_i$ is data that pollsters have taken which tells us their estimate of people voting for Romney and $x_i$ is the fraction of religious people in county $i$. Because poll samples are finite, there is a margin of error on each data point or county $i$, but we will ignore that for now."
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"Let us assume that we have a \"population\" of 200 counties $x$:"
]
},
{
"cell_type": "code",
"execution_count": 28,
"metadata": {},
"outputs": [
{
"data": {
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