Positive bias refers to the human tendency to look for observations where a theory can explain, rather than making sure that observations that cannot be explained do not occur. In this case, it refers to Hermione coming up with number triplets that follow the particular rule, rather than trying to find any triplets that do not follow the rule, and would disconfirm her theory if they do.
Not to be confused with Confirmation bias.
Detailed chapter synopsisEdit
Hermione is reading the history of Hogwarts while thinking about her awkward feeling about dealing with people outside of learning or helping topics are described. She stops reading to answer Harry Potter's question for a girl named Hermione Granger. Although she didn't say it directly, Harry still recognizes her, after which she recognizes him from multiple books. She recapitulates his biography, arousing Harry's interest. They start a test on how much Hermoine remembers of the books she has been reading, which she can in much detail. After this, Harry offers her a drink and asks her to join him in his Project to find out how magic works and can be used to help society. To prove he's as intelligent as he states, he claims that he can perform magic by snapping his fingers. Upon earing this Hermoine couths the drink on her new clothes, which indeed turn clean after his fingers snapped. He then states that it was a trick, but Hermoine should investigate it. Hermione uses the scientific method: 1. Form a hypothesis; 2. Do an experiment to test the hypothesis; 3. Measure the results; 4. Make a cardboard poster. After testing the theory that the robes are charmed to clean themselves with the same drink, Harry points out that her answer is wrong, by explaining Positive Bias; people tend to think of making experiments proving their hypothesis, not disproving it. After this Hermione retests with another liquid and realises that Harry's drink has this effect.
They get interrupted by Neville, who is searching for his pet toad. Harry gives the hint to ask some authorities. Then Neville remembers an event where Harry, Fred, and George scared him; after Neville leaves, Harry explained that only the consequences can determine if an act was good or bad, which in this case would cause no harm. They again get interrupted by Neville, whining about a Gryffindor prefect who does not take his concern seriously, which engages Harry to help him, leaving Hermoine back questioning the good traits of Gryffindor.
The disclaimer is a reference to Arthur C. Clarke's novel 2010: Odyssey Two. The original quote is ALL THESE WORLDS ARE YOURS—EXCEPT EUROPA. ATTEMPT NO LANDINGS THERE.