PHIL105_2022Spring_Assignment (2)

PHIL 105: CRITICAL THINKING (2022 SPRING) ASSIGNMENT: HYPOTHESIS TESTING (5% + 20%) Assignment meeting with Lyle (5%) : Class 9 (March 10) Assignment (PDF file uploaded to Moodle) (20%) : Sunday, March 20, 23:59 ASSIGNMENT PART 1: Observation, Question, and Hypotheses a) Observation (30 words max) Describe a fact or event reported in a news article. The event may have happened anytime but the article must be published since 2021 Dec 1. Cite this news article (Title, Date, Publisher, URL) with a note* at the bottom of this section. * “Interesting Event Happens”, 2022 Jan 15, The Gotham Herald (www.gothamherald.com/2022/01/15/world/interesting-event-happens.html) b) Context (150 words max) Give some details from the article about the fact or event. You may also use one additional source. c) Explanatory Question (25 words max) Ask a specific question about your observation. This could be simply “Why did [event] happen?” , or a “What” or “How” question. d) Hypothesis 1 and an Alternative Hypothesis 2 (25 words max each) State H1 and H2. These are two different competing answers to your explanatory question. • Note: Here “ c ompeting” means that common sense tells you that H1 and H2 are not both true , even if it is technically impossible that both are true. e) Prior Probabilities (150 words max) State the probabilities P (H1) and P (H2). Say why the probabilities you give are reasonable. Prior probabilities are based on the event or fact being explained, background information, hypothesis simplicity, and whether there are alternative explanations. These numbers are your own judgements of how likely H1 and H2 are. They are not calculations; they are not numbers you find in news articles. • Note: It is possible that P (H1) + P (H2) = 1. However assigning probabilities like this is very extreme because it denies all other hypotheses! Normally P (H1) + P (H2) < 1.

PART 2: New Evidence a) New Evidence for H1 (25 words max) State E. Describe a piece of new evidence that could be either discovered or not, and would either confirm or disconfirm H1. “ New ” means that the prior P (H1) was not based on E. Evidence E or ¬E is information that would update the probability of H1. b) Evidence Strength (150 words max) State the probabilities P (E | H1) and P (E | ¬H1). Calculate the E evidence strength and describe it as strongly/moderately/weakly confirming/disconfirming. Say why the probabilities and evidence strength you give are reasonable. PART 3: Updating H1 Probability a) Bayes Box Draw a Bayes Box for H1 and E. Visually estimate the updated odds of H1 given E, and the updated odds of H1 given ¬E. • Note: Your diagram does not have to be perfect – I will not measure it with a ruler. But it should be clear, labelled, and large enough for you and I to inspect easily. b) Bayes ’ Rule Imagine you learn that E is true. Write Bayes ’ Rule for P (H1 | E) and calculate the updated probability. Check that it matches your estimate with the diagram. Imagine you learn that E is false (¬E). Write Bayes ’ Rule for P (H1 | ¬E) and calculate the updated probability. Check that it matches your estimate with the diagram. MEETING WITH LYLE – CLASS 9 (MAR 10) Our meeting will be about 5 minutes. For the meeting, you need to bring a draft of the following sections: 1a , 1c , 1d , and 2a . You may revise these sections after we discuss them at the meeting. The meeting mark is based on you making a serious attempt to do the tasks in these sections and coming to the meeting prepared to tell me about what your research and thoughts for these sections.