diff --git a/api_docs.ipynb b/api_docs.ipynb
deleted file mode 100644
index 790de15..0000000
--- a/api_docs.ipynb
+++ /dev/null
@@ -1,60 +0,0 @@
-{
- "cells": [
-  {
-   "cell_type": "code",
-   "execution_count": 1,
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "from policyengine import Simulation"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "sim = Simulation(\n",
-    "    country=\"uk\",\n",
-    "    scope=\"macro\",\n",
-    "    time_period=2025,\n",
-    "    reform={\n",
-    "        \"gov.hmrc.income_tax.allowances.personal_allowance.amount\": {\n",
-    "            \"2025\": 0,\n",
-    "        }\n",
-    "    }\n",
-    ")\n",
-    "sim.calculate(\"macro\")"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {},
-   "outputs": [],
-   "source": []
-  }
- ],
- "metadata": {
-  "kernelspec": {
-   "display_name": "base",
-   "language": "python",
-   "name": "python3"
-  },
-  "language_info": {
-   "codemirror_mode": {
-    "name": "ipython",
-    "version": 3
-   },
-   "file_extension": ".py",
-   "mimetype": "text/x-python",
-   "name": "python",
-   "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython3",
-   "version": "3.10.14"
-  }
- },
- "nbformat": 4,
- "nbformat_minor": 2
-}
diff --git a/docs/_toc.yml b/docs/_toc.yml
index b2699f2..51cd2ae 100644
--- a/docs/_toc.yml
+++ b/docs/_toc.yml
@@ -3,4 +3,7 @@ root: index
 parts:
   - caption: Maintenance
     chapters:
-    - file: maintaining
\ No newline at end of file
+    - file: maintaining
+  - caption: Schema
+    chapters:
+    - file: schema
\ No newline at end of file
diff --git a/docs/schema.ipynb b/docs/schema.ipynb
new file mode 100644
index 0000000..89ed21b
--- /dev/null
+++ b/docs/schema.ipynb
@@ -0,0 +1,140 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Schema\n",
+    "\n",
+    "This page contains examples of the schema of the returned simulation outputs for given types of simulation. Each subsection specifies the country, scope and whether a reform has been passed. The schema is given in YAML format.\n",
+    "\n",
+    "## UK, macro, reform-comparison"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "tags": [
+     "hide-input"
+    ]
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/markdown": [
+       "```yaml\n",
+       "macro:\n",
+       "  baseline:\n",
+       "    gov:\n",
+       "      balance:\n",
+       "        total_gov_spending: <class 'numpy.float64'>\n",
+       "        total_state_tax: <class 'int'>\n",
+       "        total_tax_revenue: <class 'numpy.float64'>\n",
+       "      programs:\n",
+       "        child_benefit: <class 'numpy.float64'>\n",
+       "        council_tax: <class 'numpy.float64'>\n",
+       "        fuel_duty: <class 'numpy.float64'>\n",
+       "        income_tax: <class 'numpy.float64'>\n",
+       "        national_insurance: <class 'numpy.float64'>\n",
+       "        ni_employer: <class 'numpy.float64'>\n",
+       "        pension_credit: <class 'numpy.float64'>\n",
+       "        state_pension: <class 'numpy.float64'>\n",
+       "        tax_credits: <class 'numpy.float64'>\n",
+       "        universal_credit: <class 'numpy.float64'>\n",
+       "        vat: <class 'numpy.float64'>\n",
+       "    household:\n",
+       "      demographic_values:\n",
+       "        household_count_people: <class 'list'>\n",
+       "        household_weight: <class 'list'>\n",
+       "        person_weight: <class 'list'>\n",
+       "  comparison:\n",
+       "    revenue_impact:\n",
+       "      tax_revenues: <class 'numpy.float64'>\n",
+       "  reform:\n",
+       "    gov:\n",
+       "      balance:\n",
+       "        total_gov_spending: <class 'numpy.float64'>\n",
+       "        total_state_tax: <class 'int'>\n",
+       "        total_tax_revenue: <class 'numpy.float64'>\n",
+       "      programs:\n",
+       "        child_benefit: <class 'numpy.float64'>\n",
+       "        council_tax: <class 'numpy.float64'>\n",
+       "        fuel_duty: <class 'numpy.float64'>\n",
+       "        income_tax: <class 'numpy.float64'>\n",
+       "        national_insurance: <class 'numpy.float64'>\n",
+       "        ni_employer: <class 'numpy.float64'>\n",
+       "        pension_credit: <class 'numpy.float64'>\n",
+       "        state_pension: <class 'numpy.float64'>\n",
+       "        tax_credits: <class 'numpy.float64'>\n",
+       "        universal_credit: <class 'numpy.float64'>\n",
+       "        vat: <class 'numpy.float64'>\n",
+       "    household:\n",
+       "      demographic_values:\n",
+       "        household_count_people: <class 'list'>\n",
+       "        household_weight: <class 'list'>\n",
+       "        person_weight: <class 'list'>\n",
+       "\n",
+       "```"
+      ],
+      "text/plain": [
+       "<IPython.core.display.Markdown object>"
+      ]
+     },
+     "execution_count": 1,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "from policyengine import Simulation\n",
+    "from IPython.display import Markdown\n",
+    "import yaml\n",
+    "\n",
+    "def replace_value_with_dtype(tree):\n",
+    "    for key in tree:\n",
+    "        if isinstance(tree[key], dict):\n",
+    "            replace_value_with_dtype(tree[key])\n",
+    "        else:\n",
+    "            tree[key] = str(type(tree[key]))\n",
+    "    return tree\n",
+    "\n",
+    "sim = Simulation(\n",
+    "    country=\"uk\",\n",
+    "    scope=\"macro\",\n",
+    "    time_period=2025,\n",
+    "    reform={\n",
+    "        \"gov.hmrc.income_tax.allowances.personal_allowance.amount\": {\n",
+    "            \"2025\": 0,\n",
+    "        }\n",
+    "    }\n",
+    ")\n",
+    "sim.calculate(\"macro\")\n",
+    "tree = replace_value_with_dtype(sim.outputs)\n",
+    "\n",
+    "Markdown('```yaml\\n' + yaml.dump(tree, indent=2) + '\\n```')"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "base",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.10.14"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}
diff --git a/policyengine/outputs/macro/comparison/revenue_impact.py b/policyengine/outputs/macro/comparison/revenue_impact.py
index 4403c3a..9cce7be 100644
--- a/policyengine/outputs/macro/comparison/revenue_impact.py
+++ b/policyengine/outputs/macro/comparison/revenue_impact.py
@@ -16,4 +16,7 @@ def revenue_impact(simulation: Simulation):
     tax_revenue_reform = simulation.calculate(
         "macro/reform/gov/balance"
     )["total_tax_revenue"]
-    return tax_revenue_reform - tax_revenue_baseline
+    tax_revenue_impact = tax_revenue_reform - tax_revenue_baseline
+    return {
+        "tax_revenues": tax_revenue_impact,
+    }
diff --git a/test.ipynb b/test.ipynb
deleted file mode 100644
index b82cee8..0000000
--- a/test.ipynb
+++ /dev/null
@@ -1,75 +0,0 @@
-{
- "cells": [
-  {
-   "cell_type": "code",
-   "execution_count": 1,
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "from policyengine import Simulation"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 2,
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "sim = Simulation(\n",
-    "    country=\"uk\",\n",
-    "    scope=\"macro\",\n",
-    "    time_period=2025,\n",
-    "    reform={\n",
-    "        \"gov.hmrc.income_tax.allowances.personal_allowance.amount\": {\n",
-    "            \"2025\": 0,\n",
-    "        }\n",
-    "    }\n",
-    ")"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": 5,
-   "metadata": {},
-   "outputs": [
-    {
-     "ename": "KeyError",
-     "evalue": "'comparison'",
-     "output_type": "error",
-     "traceback": [
-      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
-      "\u001b[0;31mKeyError\u001b[0m                                  Traceback (most recent call last)",
-      "\u001b[0;32m/var/folders/r_/j9kk4vmd3tj29ljn52_76m4h0000gn/T/ipykernel_62469/2089930413.py\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0msim\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mcalculate\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m\"macro\"\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
-      "\u001b[0;32m~/policyengine/policyengine.py/policyengine/simulation.py\u001b[0m in \u001b[0;36mcalculate\u001b[0;34m(self, output)\u001b[0m\n\u001b[1;32m     89\u001b[0m         \u001b[0;32mif\u001b[0m \u001b[0misinstance\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mnode\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mdict\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     90\u001b[0m             \u001b[0;32mfor\u001b[0m \u001b[0mchild_key\u001b[0m \u001b[0;32min\u001b[0m \u001b[0mnode\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mkeys\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m---> 91\u001b[0;31m                 \u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mcalculate\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0moutput\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0;34m\"/\"\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0mchild_key\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m     92\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     93\u001b[0m         \u001b[0;32mreturn\u001b[0m \u001b[0mnode\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
-      "\u001b[0;32m~/policyengine/policyengine.py/policyengine/simulation.py\u001b[0m in \u001b[0;36mcalculate\u001b[0;34m(self, output)\u001b[0m\n\u001b[1;32m     79\u001b[0m         \u001b[0mparent\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mnode\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     80\u001b[0m         \u001b[0mchild_key\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0moutput\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0msplit\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m\"/\"\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0;34m-\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m---> 81\u001b[0;31m         \u001b[0mnode\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mparent\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mchild_key\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m     82\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     83\u001b[0m         \u001b[0;31m# Check if any descendants are None\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
-      "\u001b[0;31mKeyError\u001b[0m: 'comparison'"
-     ]
-    }
-   ],
-   "source": [
-    "sim.calculate(\"macro\")"
-   ]
-  }
- ],
- "metadata": {
-  "kernelspec": {
-   "display_name": "base",
-   "language": "python",
-   "name": "python3"
-  },
-  "language_info": {
-   "codemirror_mode": {
-    "name": "ipython",
-    "version": 3
-   },
-   "file_extension": ".py",
-   "mimetype": "text/x-python",
-   "name": "python",
-   "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython3",
-   "version": "3.10.14"
-  }
- },
- "nbformat": 4,
- "nbformat_minor": 2
-}