incorporating TR comments in ch 1

content/ch/01/lifecycle_cycle.ipynb

@@ -74,12 +74,9 @@
    "source": [
     "*Obtain Data.* When data are expensive and hard to gather and when our aim is to generalize from the data to the world, we aim to define precise protocols for collecting the data. Other times, data are cheap and easily accessed.\n",
     "This is especially true for online data sources.\n",
-    "For example, Twitter lets people quickly download millions of data\n",
-    "points [^twitter].\n",
+    "For example, [Twitter](https://developer.twitter.com/en/docs/twitter-api) lets people quickly download millions of data points.\n",
     "When data are plentiful, we can start an analysis by obtaining data, exploring it, and then honing a research question.\n",
-    "In both situations, most data have missing or unusual values and other anomalies that we need to account for. No matter the source, we need to check the data quality. And, typically, we must manipulate the data before we can analyze it more formally. We may need to modify structure, clean data values, and transform measurements to prepare for analysis.\n",
-    "\n",
-    "[^twitter]: https://developer.twitter.com/en/docs/twitter-api"
+    "In both situations, most data have missing or unusual values and other anomalies that we need to account for. No matter the source, we need to check the data quality. Considering the scope of the data is equally important; for example, we identify how representative the data are and look for potential sources of bias in the collection process. These considerations help us determine how much faith we can place in our findings. And, typically, we must manipulate the data before we can analyze it more formally. We may need to modify structure, clean data values, and transform measurements to prepare for analysis."
    ]
   },
   {