IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: BoyFromTheFuture on May 13, 2010, 11:29:34 pm

Title: Bio P5 doubt
Post by: BoyFromTheFuture on May 13, 2010, 11:29:34 pm

O/N/07 Q3(b)(ii)
How do I find the probability of the chi-squared value?

Title: Re: Bio P5 doubt
Post by: khi2ruh on May 13, 2010, 11:45:09 pm

u knw how to find the degrees of freedom and the chi-squared value right?
so the degrees of freedom re two and the chisquared value is 39.9,look at the values for the degrees of freedom in the table, 39.9 is greater than 13.82 which is the highest corresponding value for 2 degrees of freedom.Hence, 0.001 which corresponds to 13.82 in the table is the probability of the chisquaredvalue.

Hope this helps.im not particularly good at explaining.

Title: Re: Bio P5 doubt
Post by: MaNi_DaDuDe on May 14, 2010, 12:14:39 am

Quote from: khi2ruh on May 13, 2010, 11:45:09 pm

u knw how to find the degrees of freedom and the chi-squared value right?
so the degrees of freedom re two and the chisquared value is 39.9,look at the values for the degrees of freedom in the table, 39.9 is greater than 13.82 which is the highest corresponding value for 2 degrees of freedom.Hence, 0.001 which corresponds to 13.82 in the table is the probability of the chisquaredvalue.

Hope this helps.im not particularly good at explaining.

I understood quite well. Thanks! :)

+rep'd ;)

Title: Re: Bio P5 doubt
Post by: BoyFromTheFuture on May 14, 2010, 12:31:39 am

Same here.
also rep'd.
Thanks a lot.

Now for the next part (iii)
I understand what is asked from me, but what I don't know is how to conclude that the result is significant or not due to chance.

Title: Re: Bio P5 doubt
Post by: CHEMMASTER6000 on May 14, 2010, 02:31:32 am

you value for chi squared is  39.9 and your degree of freedom should be 2. now the critical value for a freedom of two as stated on the  table. 39.9 shows a value more then 0.05 or 5% chance probability . thus the probablility of the data occuring due to chance is very low. in this case we can state the probablility to be 0.001 chance since at that probability the critical value is 13.82 and is closest to 39.9 ;D pm me if you have any doubts . only a couple of hours left

Title: Re: Bio P5 doubt
Post by: khi2ruh on May 14, 2010, 10:48:24 am

Quote from: BoyFromTheFuture on May 14, 2010, 12:31:39 am

Same here.
also rep'd.
Thanks a lot.

Now for the next part (iii)
I understand what is asked from me, but what I don't know is how to conclude that the result is significant or not due to chance.

so u still need an answer or are u thru with the paper?