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

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: VIP_93 on May 13, 2010, 07:55:17 am

Title: biology paper 5
Post by: VIP_93 on May 13, 2010, 07:55:17 am

plz i have a question....
wat's the difference between t test and chi square?? in terms of degrees of freedom and probability??? and wen can we know if there's a significant difference ....and the critical value???
plz i am totally confused
thx in advance....

Title: Re: biology paper 5
Post by: osmosis on May 13, 2010, 08:51:36 am

t-test determine the significance of the difference between two means, such as comparing the two means obtained from two samples from a population.
chi-squared test is applied to some cases of data showing discontinuous distribution, like the genetic cross. (where the test can show the if the observed results are significantly different from the results that would be expected from genetic principles..

for the number of degree of freedom and probability, you just have to refer to the table given.
number of degree of freedom= number of classes-1
to know whether there is a significant difference, look at the probability 0.05 (the critical value). this is the probability due to chance.
if the probability that you get is greater than the critical value (0.05), meaning high probability due to chance. so the difference is not significant.
if the probability that you get is less than the critical value (0.05), meaning less probability that the difference is due to chance...therefore the difference is significant....
I HOPE YOU UNDERSTAND!!!! :)

Title: Re: biology paper 5
Post by: MaNi_DaDuDe on May 13, 2010, 09:20:25 am

Quote from: osmosis on May 13, 2010, 08:51:36 am

t-test determine the significance of the difference between two means, such as comparing the two means obtained from two samples from a population.
chi-squared test is applied to some cases of data showing discontinuous distribution, like the genetic cross. (where the test can show the if the observed results are significantly different from the results that would be expected from genetic principles..

for the number of degree of freedom and probability, you just have to refer to the table given.
number of degree of freedom= number of classes-1
to know whether there is a significant difference, look at the probability 0.05 (the critical value). this is the probability due to chance.
if the probability that you get is greater than the critical value (0.05), meaning high probability due to chance. so the difference is not significant.
if the probability that you get is less than the critical value (0.05), meaning less probability that the difference is due to chance...therefore the difference is significant....
I HOPE YOU UNDERSTAND!!!! :)

Thanks, +rep. :D

Title: Re: biology paper 5
Post by: osmosis on May 13, 2010, 09:31:34 am

you're welcome! :)

Title: Re: biology paper 5
Post by: VIP_93 on May 13, 2010, 06:07:43 pm

thx a lot osmosis...+Rep

Title: Re: biology paper 5
Post by: HOUSE_MUSIC on May 13, 2010, 06:58:37 pm

hey VIP_93 can u give me ur e-mail ?

Title: Re: biology paper 5
Post by: VIP_93 on May 13, 2010, 08:35:39 pm

cool_roony_95@hotmail.co.uk