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eric: In the cingulotomy research, which of the following would be important to know to assess the effectiveness of an MRI-guided cingulotomy for treating psychiatric disease?i) The fraction of psychiatric patients in general who recover from severe psychiatric symptoms that last a year or longer. ii) The effect of a cingulotomy on people without mental illness.iii) The number of patients whose follow-up evaluations were based on letters from them, rather than assessments by a psychiatrist.Megan Goldman: What do you think on this one?eric: i realized that this was in one of the previous hw tooeric: so iget why i) is trueeric: and ii)eric: but not iii), lolMegan Goldman: Right, that'll help sort out if this treatment has any different effect from whatever most psych patients are doing.eric: iii seems somehow irrelevant to me?Megan Goldman: Well, the follow-up from letters isn't as reliable as from a psychiatrist.Megan Goldman: If it turns out that a huge portion of the follow-up was done with letters, it may call teh results into question.Megan Goldman: Patients may tend to over/understate their symptoms when self-reporting.eric: oh i seeeric: is this correct if i call this response bias?Megan Goldman: Self-reporting is prone to response bias, yes.eric: right ,okayeric: coolSean: Hi MeganSean: can I ask you about question 20 on Final 3?Megan Goldman: Sure.Sean: it's the which of the "following is closest ..." one Sean: I think I'm supposd to use the inequalities here, but ISean: 'm kinda confusedSean: i tried doing 16292.64/3992.655
Sean: to get ~4Sean: then 1/4^2Sean: and got abou 6.25%Sean: am i supposed to subtract that from 100% to get the right answer?Sean: I was using chebychev's inequalityMegan Goldman: Let me noodle it out real quick.Megan Goldman: you've almost got Chebyshev right... it measures the distance from the mean, so you'll want (16292.64 - 3915.413)/3992.655 to get a value for k.Megan Goldman: Then do 1/k^2 to find a probability....Recall that the probability is the chance of being *outside* that many SDs from the mean.Sean: oh so there is ~10% chance that it's that many SDs outside from the meanMegan Goldman: So yes, you'll want 1 - that probability to find the chance you're less than that many SDs away.Megan Goldman: Right.Sean: icicSean: for the 16292.64-3915 / 3992.655 partSean: is that converting to SU?Megan Goldman: Basically, yes.Sean: i seeSean: thank you :)Megan Goldman: No prob.Tina: Hi meganMegan Goldman: HowdyTina: can you help me right now or are you with another student?Megan Goldman: No, go ahead.Tina: oh ok well I'm having trouble on Q6Tina: finding the P-valueTina: I know how to find Z
Megan Goldman: Alright. did you get an answer to Q5?Tina: yesMegan Goldman: We're not on to z yet here... that would be using teh normal approximation for Fisher's Exact Test. Here, we're using Fisher without approximation.