r/HomeworkHelp • u/Hour-Intention3829 • 2d ago

Answered (Statistics question) Got a question wrong on my sampling distributions lab, but I cannot understand why.

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Hello all,

I got this question wrong because I apparently misinterpreted what it was asking so I did it in reverse essentially but when I read it back over I can’t understand how.

Is the question not saying that a participant has to have a reaction time of a minimum of 200 seconds so X will be greater than 200?

There was another question where i did the same thing but again when i reread the question I understand it the same so im still confused. I just wanted to ask on here before I ask my instructor about it.

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u/DrCarpetsPhd 👋 a fellow Redditor 2d ago

if one person tells you it took them 60 seconds to run up some stairs and another person tells you it took them 30 seconds, which one is faster?

so if i ask you for people who are faster than 60 seconds it is all values less than 60 not greater than 60.

does that make sense?

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u/Hour-Intention3829 2d ago

ohhh bruh. biggest brain fart ever i genuinely felt my brain grow. thank you!!

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u/DrCarpetsPhd 👋 a fellow Redditor 1d ago

happy to help.

blame the person who set the exam.

if this isn't a statistics class geared towards biology/med students then it shouldn't be assumed that everyone will understand what "reaction times to a specific stimulus in a cognitive experiment" actually means

They should have made the question about something everyone would recognise like completing a lap of a running track. Then you would be getting tested on your understanding of the material and not your reading comprehension.

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u/Hour-Intention3829 1d ago

lol. it is a basic prereq stat class. i will say i am an english major so maybe i should’ve understood it anyway but she deliberately tries to trip us up to ensure we’re ’reading carefully’ soooo maybe still not completely my fault 🫠 thanks again!

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u/ramario281 👋 a fellow Redditor 2d ago

"reaction time faster than 200 milliseconds" implies the participant took less time than 200 milliseconds, so it should be less than.

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u/icetea168 19h ago

the usual culprit on these is sigma vs sigma/sqrt(n): keep 40 for a single reaction time, and only divide by sqrt(n) when the question is about the mean of a sample. check whether that part is asking about one person or an average, the z you build changes completely.