fix incorrect inequality

Author: djv

Chapter2_MorePyMC/MorePyMC.ipynb

@@ -670,7 +670,7 @@
       "\n",
       "### A Simple Case\n",
       "\n",
-      "As this is a hacker book, we'll continue with the web-dev example. For the moment, we will focus on the analysis of site A only. Assume that there is a true $0 \\lt p_A \\gt 1$ probability that users who, upon shown site A, eventually purchase from the site. This is the true effectiveness of site A. Unfortunately, this quantity is unknown to us. \n",
+      "As this is a hacker book, we'll continue with the web-dev example. For the moment, we will focus on the analysis of site A only. Assume that there is a true $0 \\lt p_A \\lt 1$ probability that users who, upon shown site A, eventually purchase from the site. This is the true effectiveness of site A. Unfortunately, this quantity is unknown to us. \n",
       "\n",
       "Suppose site A was shown to $N$ people, and $n$ people purchased from the site. The *observed frequency* $\\frac{n}{N}$ does not necessarily equal $p_A$ -- there is a difference between the *observed frequency* and the *true frequency* of an event. The true frequency can be interpreted as the probability of an event occurring. For example, the true frequency of rolling a 1 on a 6-sided die is 0.166. Knowing the frequency of events like fraction of users who make purchases, frequency of social attributes, percent of internet users with cats etc. are common requests we ask of Nature. Unfortunately, in general Nature hides the true frequency from us and we must *infer* it from observed data.\n",
       "\n",
@@ -2437,4 +2437,4 @@
    "metadata": {}
   }
  ]
-}
+}