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| 1 | +{ |
| 2 | + "cells": [ |
| 3 | + { |
| 4 | + "cell_type": "markdown", |
| 5 | + "metadata": { |
| 6 | + "id": "7HCJkA2ifjEk" |
| 7 | + }, |
| 8 | + "source": [ |
| 9 | + "# Simulation on Orthogonal Estimation\n" |
| 10 | + ] |
| 11 | + }, |
| 12 | + { |
| 13 | + "cell_type": "markdown", |
| 14 | + "metadata": { |
| 15 | + "id": "4sldk16nfXw9" |
| 16 | + }, |
| 17 | + "source": [ |
| 18 | + "We compare the performance of the naive and orthogonal methods in a computational experiment where\n", |
| 19 | + "$p=n=100$, $\\beta_j = 1/j^2$, $(\\gamma_{DW})_j = 1/j^2$ and $$Y = 1 \\cdot D + \\beta' W + \\epsilon_Y$$\n", |
| 20 | + "\n", |
| 21 | + "where $W \\sim N(0,I)$, $\\epsilon_Y \\sim N(0,1)$, and $$D = \\gamma'_{DW} W + \\tilde{D}$$ where $\\tilde{D} \\sim N(0,1)/4$.\n", |
| 22 | + "\n", |
| 23 | + "The true treatment effect here is 1. From the plots produced in this notebook (estimate minus ground truth), we show that the naive single-selection estimator is heavily biased (lack of Neyman orthogonality in its estimation strategy), while the orthogonal estimator based on partialling out, is approximately unbiased and Gaussian." |
| 24 | + ] |
| 25 | + }, |
| 26 | + { |
| 27 | + "cell_type": "code", |
| 28 | + "execution_count": null, |
| 29 | + "metadata": { |
| 30 | + "id": "dSvVz5Z6D14H", |
| 31 | + "vscode": { |
| 32 | + "languageId": "r" |
| 33 | + } |
| 34 | + }, |
| 35 | + "outputs": [], |
| 36 | + "source": [ |
| 37 | + "install.packages(\"hdm\")\n", |
| 38 | + "install.packages(\"ggplot2\")" |
| 39 | + ] |
| 40 | + }, |
| 41 | + { |
| 42 | + "cell_type": "code", |
| 43 | + "execution_count": null, |
| 44 | + "metadata": { |
| 45 | + "vscode": { |
| 46 | + "languageId": "r" |
| 47 | + } |
| 48 | + }, |
| 49 | + "outputs": [], |
| 50 | + "source": [ |
| 51 | + "library(hdm)\n", |
| 52 | + "library(ggplot2)" |
| 53 | + ] |
| 54 | + }, |
| 55 | + { |
| 56 | + "cell_type": "code", |
| 57 | + "execution_count": null, |
| 58 | + "metadata": { |
| 59 | + "_execution_state": "idle", |
| 60 | + "_uuid": "051d70d956493feee0c6d64651c6a088724dca2a", |
| 61 | + "id": "fAe2EP5VCFN_", |
| 62 | + "vscode": { |
| 63 | + "languageId": "r" |
| 64 | + } |
| 65 | + }, |
| 66 | + "outputs": [], |
| 67 | + "source": [ |
| 68 | + "# Initialize constants\n", |
| 69 | + "B <- 10000 # Number of iterations\n", |
| 70 | + "n <- 100 # Sample size\n", |
| 71 | + "p <- 100 # Number of features\n", |
| 72 | + "\n", |
| 73 | + "# Initialize arrays to store results\n", |
| 74 | + "Naive <- rep(0, B)\n", |
| 75 | + "Orthogonal <- rep(0, B)\n", |
| 76 | + "\n", |
| 77 | + "\n", |
| 78 | + "lambdaYs <- rep(0, B)\n", |
| 79 | + "lambdaDs <- rep(0, B)\n", |
| 80 | + "\n", |
| 81 | + "for (i in 1:B) {\n", |
| 82 | + " # Generate parameters\n", |
| 83 | + " beta <- 1 / (1:p)^2\n", |
| 84 | + " gamma <- 1 / (1:p)^2\n", |
| 85 | + "\n", |
| 86 | + " # Generate covariates / random data\n", |
| 87 | + " X <- matrix(rnorm(n * p), n, p)\n", |
| 88 | + " D <- X %*% gamma + rnorm(n) / 4\n", |
| 89 | + "\n", |
| 90 | + " # Generate Y using DGP\n", |
| 91 | + " Y <- D + X %*% beta + rnorm(n)\n", |
| 92 | + "\n", |
| 93 | + " # Single selection method\n", |
| 94 | + " rlasso_result <- hdm::rlasso(Y ~ D + X) # Fit lasso regression\n", |
| 95 | + " sx_ids <- which(rlasso_result$coef[-c(1, 2)] != 0) # Selected covariates\n", |
| 96 | + "\n", |
| 97 | + " # Check if any Xs are selected\n", |
| 98 | + " if (sum(sx_ids) == 0) {\n", |
| 99 | + " Naive[i] <- lm(Y ~ D)$coef[2] # Fit linear regression with only D if no Xs are selected\n", |
| 100 | + " } else {\n", |
| 101 | + " Naive[i] <- lm(Y ~ D + X[, sx_ids])$coef[2] # Fit linear regression with selected X otherwise\n", |
| 102 | + " }\n", |
| 103 | + "\n", |
| 104 | + " # Partialling out / Double Lasso\n", |
| 105 | + "\n", |
| 106 | + " fitY <- hdm::rlasso(Y ~ X, post = TRUE)\n", |
| 107 | + " resY <- fitY$res\n", |
| 108 | + "\n", |
| 109 | + " fitD <- hdm::rlasso(D ~ X, post = TRUE)\n", |
| 110 | + " resD <- fitD$res\n", |
| 111 | + "\n", |
| 112 | + " Orthogonal[i] <- lm(resY ~ resD)$coef[2] # Fit linear regression for residuals\n", |
| 113 | + "}" |
| 114 | + ] |
| 115 | + }, |
| 116 | + { |
| 117 | + "cell_type": "markdown", |
| 118 | + "metadata": { |
| 119 | + "id": "Bj174QuEaPb5" |
| 120 | + }, |
| 121 | + "source": [ |
| 122 | + "## Make a Nice Plot" |
| 123 | + ] |
| 124 | + }, |
| 125 | + { |
| 126 | + "cell_type": "code", |
| 127 | + "execution_count": null, |
| 128 | + "metadata": { |
| 129 | + "id": "MjB3qbGEaRnl", |
| 130 | + "vscode": { |
| 131 | + "languageId": "r" |
| 132 | + } |
| 133 | + }, |
| 134 | + "outputs": [], |
| 135 | + "source": [ |
| 136 | + "# Specify ratio\n", |
| 137 | + "img_width <- 15\n", |
| 138 | + "img_height <- img_width / 2" |
| 139 | + ] |
| 140 | + }, |
| 141 | + { |
| 142 | + "cell_type": "code", |
| 143 | + "execution_count": null, |
| 144 | + "metadata": { |
| 145 | + "id": "N7bdztt1CFOE", |
| 146 | + "vscode": { |
| 147 | + "languageId": "r" |
| 148 | + } |
| 149 | + }, |
| 150 | + "outputs": [], |
| 151 | + "source": [ |
| 152 | + "# Create a data frame for the estimates\n", |
| 153 | + "df <- data.frame(Method = rep(c(\"Naive\", \"Orthogonal\"), each = B),\n", |
| 154 | + " Value = c(Naive - 1, Orthogonal - 1))\n", |
| 155 | + "\n", |
| 156 | + "# Create the histogram using ggplot2\n", |
| 157 | + "hist_plot <- ggplot(df, aes(x = Value, fill = Method)) +\n", |
| 158 | + " geom_histogram(binwidth = 0.1, color = \"black\", alpha = 0.7) +\n", |
| 159 | + " facet_wrap(~Method, scales = \"fixed\") +\n", |
| 160 | + " labs(\n", |
| 161 | + " title = \"Distribution of Estimates (Centered around Ground Truth)\",\n", |
| 162 | + " x = \"Bias\",\n", |
| 163 | + " y = \"Frequency\"\n", |
| 164 | + " ) +\n", |
| 165 | + " scale_x_continuous(breaks = seq(-2, 1.5, 0.5)) +\n", |
| 166 | + " theme_minimal() +\n", |
| 167 | + " theme(\n", |
| 168 | + " plot.title = element_text(hjust = 0.5), # Center the plot title\n", |
| 169 | + " strip.text = element_text(size = 10), # Increase text size in facet labels\n", |
| 170 | + " legend.position = \"none\", # Remove the legend\n", |
| 171 | + " panel.grid.major = element_blank(), # Make major grid lines invisible\n", |
| 172 | + " # panel.grid.minor = element_blank(), # Make minor grid lines invisible\n", |
| 173 | + " strip.background = element_blank() # Make the strip background transparent\n", |
| 174 | + " ) +\n", |
| 175 | + " theme(panel.spacing = unit(2, \"lines\")) # Adjust the ratio to separate subplots wider\n", |
| 176 | + "\n", |
| 177 | + "# Set a wider plot size\n", |
| 178 | + "options(repr.plot.width = img_width, repr.plot.height = img_height)\n", |
| 179 | + "\n", |
| 180 | + "# Display the histogram\n", |
| 181 | + "print(hist_plot)\n" |
| 182 | + ] |
| 183 | + }, |
| 184 | + { |
| 185 | + "cell_type": "markdown", |
| 186 | + "metadata": { |
| 187 | + "id": "8hrJ3M5mrD8_" |
| 188 | + }, |
| 189 | + "source": [ |
| 190 | + "As we can see from the above bias plots (estimates minus the ground truth effect of 1), the double lasso procedure concentrates around zero whereas the naive estimator does not." |
| 191 | + ] |
| 192 | + } |
| 193 | + ], |
| 194 | + "metadata": { |
| 195 | + "colab": { |
| 196 | + "provenance": [] |
| 197 | + }, |
| 198 | + "kernelspec": { |
| 199 | + "display_name": "R", |
| 200 | + "language": "R", |
| 201 | + "name": "ir" |
| 202 | + }, |
| 203 | + "language_info": { |
| 204 | + "codemirror_mode": "r", |
| 205 | + "file_extension": ".r", |
| 206 | + "mimetype": "text/x-r-source", |
| 207 | + "name": "R", |
| 208 | + "pygments_lexer": "r", |
| 209 | + "version": "3.6.3" |
| 210 | + } |
| 211 | + }, |
| 212 | + "nbformat": 4, |
| 213 | + "nbformat_minor": 0 |
| 214 | +} |
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