A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 one year ago
Statistics/Probability questions...
1) How do I tell if the model accurately predicted the sales?
2) What is the "p" in this problem/what do I do with it? : "Assume p = 0.05"
___
I attached the full problem and a clearer version of what I think is called a 'Chi Squared Critical Values Chart.'
___
Could someone run me through how to do this problem?
anonymous
 one year ago
Statistics/Probability questions... 1) How do I tell if the model accurately predicted the sales? 2) What is the "p" in this problem/what do I do with it? : "Assume p = 0.05" ___ I attached the full problem and a clearer version of what I think is called a 'Chi Squared Critical Values Chart.' ___ Could someone run me through how to do this problem?

This Question is Closed

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1you shd start by finding the degree of freedom do u know how to do that?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0No, I don't. I asked my proctor to help me, but he didn't know how either.

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1ok there a formula for that (C1)(R1) where C represent the total # of column and R represent the total # of rows

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1no there 2 columns the expected and the observed ....and there 3 row.,vanilla, strawberry and chocolate

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1correct now take away and then multiply out the brackets to get the df

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1correct the next step is to find the chi square value and there a formula for that also

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1so we plug in the respective values in the formula and add them up note: we do them separately i will start u will finish it ok

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Sounds good, thanks a bunch :)

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1yes but we usually take the decimal in statistics

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1which is 6.894857 now this is ur chi square value

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0what now? is this where that "p" comes in?

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1now the want the p value so we take the degree of freedom which is 2 and at p=0.05 which i dont see on this chi square tables??

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1im seeing 0.005 on the table not 0.05

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1and it there twice the table have a fault

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1u see it? im assuming that the first 0.005 suppose to be 0.05??

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Maybe it is supposed to be the 5th column?

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1no actually there shdnt have the same p value on a chi square table

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0You're the expert; I'm in Algebra II. My proctor didn't know why it was included, and couldn't help me with it because he didn't know how to do stats either. There wasn't even a review or notes or anything, just questions. :/

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1im lookin at my chi square table and well the p value for 0.05 corresponds to the first 0.005 on your chi sq. table so lets used that 0k

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1so dw:1435293790254:dw

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1now we compare the 2 chi square value

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0oh wait, so that was right? Because 6.83 > 5.99, the correct answer is either A or D?

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1the answer shd be D because the p value was too low

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Both A and D say x was too low

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1ok u see what the difference between the two values?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0One says yes, and the other says no?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0referring to whether or not the model predicted the milkshake sales accurately

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0but i don't know how to tell that from our data/if it should be yes or no

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1and there a saying that goes like this....if the pvalue is low H0 must go and if the pvalue is high then h0 can fly

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1ok the difference between the value is 0.84 can conclude D or A as the answer?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I understand how to get 0.84 as the difference, but not how to tell if it is Yes or No

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1ok what we actually had to look at is if p>0.05 or p<0.05

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I thought it said p=0.05 though?

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1yes but when we find the value we see if its greater ok lesser than 0.05

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1o no we were on the right track before i got mix up after watching that video that for critical value...so we do have to look at our 2 chi squared values to determine the answer

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0okay. what about them?

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1well the chi squared value is low and lets look at it this way the chi sq value doesnt equal our chi square value and once the chi squared values is too low then it says something about the test so i still think its D

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1ok maybe if we get a second opionon an this it would be nice cause i really dont know how to explain the no it was to low part @SolomonZelman

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Thanks for all of your help so far @LynFran :)

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1LynFran you're using the right formula \[\Large \chi^2 = \sum \frac{(O_i E_i)^2}{E_i}\] \[\Large \chi^2 = \frac{(O_1 E_1)^2}{E_1}+\frac{(O_2 E_2)^2}{E_2}+\frac{(O_3 E_3)^2}{E_3}\] \[\Large \chi^2 = \frac{(205175)^2}{175}+\frac{(114125)^2}{125}+\frac{(264250)^2}{250}\] \[\Large \chi^2 = 6.894857\]

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1is there a typo in the table? I see 0.005 written twice along the top

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1I'm guessing that first 0.005 should be 0.05 ?

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1ok thought so

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1Degrees of Freedom df = k1 = 31 = 2 look at the row that starts with 2 and look at the column that has 0.05 at the top

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1So we know test statistic = 6.89 critical value = 5.99

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1do you see how to finish up?

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1actually we did all of this is just how to compare and tell the correct answer part that a bit troublesome

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1Rule: if (test statistic) > (chisquare critical value), then reject the null

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1the goodness of fit test is most always right tailed. I've never seen any cases that are otherwise, but I don't know for sure since there may be some rare cases

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@jim_thompson5910 okay, reject the null, but we can't determine whether it would be option A or D. (Yes, or No)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0from the options at the bottom of this attachment

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1Null: the observed matches with the expected Alternate: the observed does not match with the expected we rejected the null, so the observed does not match with the expected The question was "did the model predict the sales correctly?" ie "does the expected and observed values match up?" so the the answer is "no". The reason why the null was rejected was because the chisquare test statistic was too high

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Ohhhh! so it's actually B I was looking at it backwards

LynFran
 one year ago
Best ResponseYou've already chosen the best response.1wasnt the chic squared values 5.99? so how come that higher than 6.89??

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Thank you both! I'll write your testimonials when I'm all done. (later tonight/early morning)

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1that 5.99 is the critical value

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1it's the cutoff point

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I greatly appreciate all the help :)

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1anything higher than that cutoff point means you reject H0

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1dw:1435292080595:dw

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1dw:1435292122002:dw
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.