Register to reply 
Probability: usual or unusual 
Share this thread: 
#1
May2812, 08:05 PM

P: 307

This isn't really a complex question more of a problem of definition. The questions I'm getting in my book are asking me to compute probabilities of various circumstances and then it asks after each one if the occurrence of the event is usual or unusual. The book has a graphic which is showing at a value of probability 1 the event will definitely occur and at 0.5 it is a 50/50 chance and then right near zero is says unlikely to occur, and of course at 0 the event is impossible. Elsewhere in the paragraph it mentions a probability of 1/1000 as being "very unlikely" but it doesn't define an "unusual event" with any sort of numerical parameter. What should I conclude then as an unusual event? Less than 0.05?
Thanks. 


#2
May2812, 11:09 PM

Homework
Sci Advisor
HW Helper
Thanks
P: 12,901

Context is everything  seems you are being asked for a value judgement.
What is usual or unusual will depend on the circumstances. Over here we give students language like: 99% = "almost certain" 95% = "likely" 68% = "probable" 34% = "possible" 5% = "unlikely" 1% = "almost never" ... for normally distributed stats. But it's all hogwash ... if a surgical procedure has a 1% chance of killing the patient but it gets performed 1000s of times a day then deaths from this procedure are very common and saying it "almost never" happens would be silly. 


#3
May2812, 11:39 PM

P: 307

Good call. Just didn't know if I was missing something key within the text. Thank you.



Register to reply 
Related Discussions  
LaTeX Font Different from Usual?  Forum Feedback & Announcements  3  
Please help. Very hard probability question with unusual wording  Calculus & Beyond Homework  1  
Not the usual GPA question (but similar)  Academic Guidance  5  
Not your usual Cavendish  Classical Physics  6  
Usual QM with 'loops'  Quantum Physics  4 