Add ATT method to the germany nb

examples/germany.ipynb

@@ -233,10 +233,44 @@
     "synth.gaps_plot(time_period=range(1960, 2004), treatment_time=1990)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Compute the average treatment effect on the treated unit (ATT) over the post-treatment time period. This method returns a standard error also."
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 7,
    "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "{'att': -1558.4329540422546, 'se': 317.5609062753852}"
+      ]
+     },
+     "execution_count": 7,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "synth.att(time_period=range(1990, 2004))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The summary function give more information on the predictor values. The first column shows the value of the $V$ matrix for each predictor, the column 'treated' shows the mean value of each predictor for the treated unit over the time period `time_predictors_prior`, the column 'synthetic' shows the mean value of each predictor for the synthetic control over the time period `time_predictors_prior` and finally the column 'sample mean' shows the sample mean of that predictor for all control units over the time period `time_predictors_prior` i.e. this is the same as the synthetic control with all weights equal."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -322,7 +356,7 @@
        "special.3.invest80   0.155     27.018     27.073       25.895"
       ]
      },
-     "execution_count": 7,
+     "execution_count": 8,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -348,7 +382,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.0"
+   "version": "3.10.4"
   },
   "orig_nbformat": 4,
   "vscode": {