Add explanatory sentence.

Author: hmgaudecker

docs/tutorials/personas.ipynb

@@ -168,8 +168,27 @@
     "        p2=0,\n",
     "        n_points=5,\n",
     "    ),\n",
-    ")\n",
-    "\n",
+    ")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "6",
+   "metadata": {},
+   "source": [
+    "Looking at the `(\"einnahmen\", \"bruttolohn_m\")` column, we see that the secondary\n",
+    "earner's earnings are varied between 1,000 and 3,000 Euro per month in steps of 500\n",
+    "Euro, while the primary earner's earnings are fixed at 4,000 Euro per month and the\n",
+    "child's earnings are 0:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "7",
+   "metadata": {},
+   "outputs": [],
+   "source": [
     "persona_with_varying_income_of_secondary_earner.input_data_tree[\"einnahmen\"][\n",
     "    \"bruttolohn_m\"\n",
     "]"
@@ -178,7 +197,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "6",
+   "id": "8",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -199,7 +218,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "7",
+   "id": "9",
    "metadata": {},
    "source": [
     "If you want to vary anything else than `bruttolohn_m`, use the upserting mechanism\n",
@@ -215,7 +234,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "8",
+   "id": "10",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -227,7 +246,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "9",
+   "id": "11",
    "metadata": {},
    "source": [
     "### Advanced Usage: Upserting Input Data\n",
@@ -251,7 +270,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "10",
+   "id": "12",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -264,7 +283,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "11",
+   "id": "13",
    "metadata": {},
    "source": [
     "Next, define the input data to upsert:\n"
@@ -273,7 +292,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "12",
+   "id": "14",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -284,7 +303,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "13",
+   "id": "15",
    "metadata": {},
    "source": [
     "Alternatively, you can generate a range of rent levels using `numpy.linspace`:"
@@ -293,7 +312,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "14",
+   "id": "16",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -310,7 +329,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "15",
+   "id": "17",
    "metadata": {},
    "source": [
     "> **The order of input data matters!** GETTSIM uses pointers to `p_id`s in the input\n",
@@ -328,7 +347,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "16",
+   "id": "18",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -339,7 +358,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "17",
+   "id": "19",
    "metadata": {},
    "source": [
     "The new persona can then be used to compute taxes and transfers:"
@@ -348,7 +367,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "18",
+   "id": "20",
    "metadata": {},
    "outputs": [],
    "source": [