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Chapter 16.4: How to do the Chi-squared test
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- Опубліковано 17 сер 2024
- The chi-squared test is used to determine if there is a significant difference between the observed ratios from an actual cross and the predicted ratios for the same cross. In this video, I show how to calculate the chi-squared value and how to interpret it using the p-statistic. I also explain how to calculate the expected number using the expected ratio.
Hello Dr. Demi
Thanks for taking the pains to make videos. I teach IGCSE, A Levels and A P Biology and I must confess that I see your videos many times to further solidify my knowledge, find an easier way to teach tough concepts and to also boost my confidence. God bless you. Hope to see more of your TedEx talks soon
Thank you very much. I read this topic in my textbook and I finding it very hard to understand. Now that I have watched this video I understand better.
Best teacher❤❤❤
I love youuu
Can you make a video on Paper 5 before the May/june exams please. Thank you for the videos btw. Will all the chapters be done before the final May/june exams ?
Hi Goku, I will do a paper 5 before the exams, but I'm not sure all the chapters will be ready before then. Will try to cover as much as possible
@@biowithdrdemi Thank you very much for your help. If possible please try to finish till chapter 18
Hi guys may l have the link of the previous video, which contains the original question .
Thank you in advance
Thank you
this is a purely hypothetical question, but what is the P value is the same as the value in the table? would we reject null or accept?
You make decisions based on whether or not the p value is less than or equal to 0.05.
Good evening Dr.Demi, please answer my question. Does that mean that when we reject the null hypothesis we’re saying that the observed and expected ratio are not related and happen by chance? And when we accept the null, there is no evidence to say that difference happen due to a specific variable so they’re not by chance and occur more often than by chance.
After a performing a test, scientists can: Reject the null hypothesis (meaning there is a definite, consequential relationship between the two phenomena), or. Fail to reject the null hypothesis (meaning the test has not identified a consequential relationship between the two phenomena)
@@ayeshamasuood4450 thank you, I wish you get the grades you want xD
@@reemjamal8866 hope you do too. Thank you ☺️❤️
Hello miss! I had this confusion regarding chi squared test, how do we calculate the expected number when they haven't given us the total number of organisms? Because I did come across questions in which the total number of organisms wasn't specified even tho we did have the ratio
The expected number is dependent on the type of cross you have. If it's a dihybrid cross, the ratio for the genotypes will be 9:3:3:1. This is the expected number. Consider watching the whole of chapter 16 if you haven't because I offer a detailed explanation in earlier videos
Thank you !
Dr Demi, the formula for degrees of freedom I am confused regarding it, will it be (n-1) + (n-1) or just (n-1)?
It depends on the test you're doing. For chi-square or any other test with one dataset, it's n-1. For the t-test, it's (n-1)
+(n-1) because there are two datasets
@@biowithdrdemi So the data set in chi square is the genotypes formed and that is one data set and since t test is comparing two means that is why it is (n-1) added twice, that is correct, Dr Demi?
@@tjveyd yes that's right
@@biowithdrdemi Thank you so much Dr. Demi for helping me. My P4 is tomorrow so just asking whatever doubts I have on your videos when I am revising!