You are Here: Home >< Maths

# Chi Squared Test watch

1. Ok, here is the data:

conditions Observable Number
Dark,Light 51
Dark,Dry 186
Wet,Light 46
Wet,Dark 177

Ok, the null hypothesis is that the conditions do not affect the observable number of woodlice seen in each environment

so expected numbers is the total divided by 4 = 115

can someone calculate chi squared and tell me what they got so i can compare?
2. wowzer i got 154.278... which seems ridiculously high, especially as the degrees of freedom is really low (3)
what did you get?
3. χ2(1) = 0.0548
p = 0.8149 (two-tailed)
4. (Original post by nellydee)
wowzer i got 154.278... which seems ridiculously high, especially as the degrees of freedom is really low (3)
what did you get?
i got that as well! for the degrees of freedom, i left out some data. here is the link to the full table. so the degrees of freedom is 18, no?

http://www.thestudentroom.co.uk/show....php?t=1164545
5. (Original post by GodspeedGehenna)
χ2(1) = 0.0548
p = 0.8149 (two-tailed)
how?! can you do a worked solution?
6. That's not how you work out the expected values.
You have to keep the column, row and grand totals the same, and work it out in ratio:
That way you can calculate

I hate stats
7. (Original post by maxfire)
That's not how you work out the expected values.
You have to keep the column, row and grand totals the same, and work it out in ratio:
That way you can calculate

I hate stats
if the null hyp says there is an equal chance that they go in any of the four areas, doesnt it mean that the expected values are just 1/4 of the total? by the way...my childhood is ruined now
8. (Original post by maxfire)
That's not how you work out the expected values.
You have to keep the column, row and grand totals the same, and work it out in ratio:
That way you can calculate

I hate stats
i think you're thinking of chi squared tests from s2, it's slightly different in s3.
9. maths make me hurt
10. (Original post by angrydanmarin)
maths make me hurt
same....

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: January 26, 2010
Today on TSR

### He broke up with me because of long distance

Now I'm moving to his city

### University open days

1. Norwich University of the Arts
Thu, 19 Jul '18
2. University of Sunderland
Thu, 19 Jul '18
3. Plymouth College of Art
Thu, 19 Jul '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams