The Chi-Squared Test - A Level Biology
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- Опубліковано 14 лип 2024
- One of the statistical tests used in A Level Biology, the Chi-squared test is used to compare observed results with expected results.
Expected results from tests can be evenly distributed or can be expected to fit certain phenotypic ratios. This video will teach you how to use the Chi-squared with and without phenotypic ratios.
- why you need to use the Chi-squared test
- how to state your null hypothesis
- how to carry out the statistical test
- find the critical value at p=0.05 (and what that means)
- how to write a conclusion.
This video includes explanation and walk-through of some practice questions.
For supporting workpack visit biologybreakdown.co.uk/product/3.
For more GCSE and A-Level content visit biologybreakdown.co.uk where you will find detailed workpacks with consolidation, knowledge recall and application questions and answers.
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Imagine if you were lucky enough to have this teacher
How lovely! Thank you! 😊
It helped me a lot thank you ! 💕
this is so well done! thank you so much! ❤️
Thank you for the lovely comment 😊💕
this came up the other day in paper 2!!
Great breakdown 👌🏾
Thank you! 😊
Love the way you teach ❤️
Thank you! 😊
My final January exam for unit 1 (edexcel) is tomorrow, thank you so much! This was the only thing I didn’t understand till now
Good luck! 🍀
@@BiologyBreakdownwithMrsH thank you! Do you have any tips for unit 3 (practical) edexcel? I’m taking the entire AS in the first semester so I study at home, alone. Is there any new material or info I need to solve unit 3 or is it just the structure of the questions that’s different? Thank you for your amazing videos anyway:)
@darkpheonix5216 hi, I’m afraid I’m not familiar with Edexcel, I’ve only taught OCR A Level. Just do as many past paper questions as you can :)
@@BiologyBreakdownwithMrsH no problem! Thank youuu
really nicely explained!!THANKSS:3
Thank you! 😊☘️
@@BiologyBreakdownwithMrsH 💞💞
thank u!
the equation is equal to x^2, why don’t you have to square root the end value of 15.59 to make it 3.94?
Hi 😊 that is a great question! I believe that some mathematicians don't like the test being called chi squared because it is misleading, as you have noticed! You may have noticed that sometimes this test is referred to as the chi square test (rather than squared) which I think is the mathematically preferred terminology but I have used squared because this is what the OCR exam board have used and I didn't want to confuse my students. Other than the misleading name of the statistical test I hope all other explanations were OK 😊
@@BiologyBreakdownwithMrsH Ahhh okay, so it’s just to denote the name of the statistical test rather than requiring you to actually square root the answer ?
Yes 😊 very misleading.
Isn't it in further stat?
Probably? Not sure what that is but Chi Squared is definitely part of the A Level Biology course 😊
from where did we get the 4 in 9:11, you divided it with 158?
The 4 came from 3+1, cuz the ratio was 3:1 for the purple:white phenotype ratio
where did you get the 1000 from? to calculate expected value
1000 is the total number of times the dice was thrown. Because we expect each side to be thrown an even number of times, we divide 1000 by 6 😊
@@BiologyBreakdownwithMrsH So like is there any specific formula or smth that can be used to calculate the expected value? Because I tend to struggle a lot with it :(
Hi, the expected value in the case of the dice is the mean (so adding all the values and dividing by how many categories there are) but most of the time in biology the expected values are in ratios as we tend to use chi squared when we do genetic crosses. Have a look back over the second part of the video where I describe how to calculate the expected ratios for 3:1 Add all the observed together and put them in proportions. If it is ratios you’re struggling with, it might be best to have a look at a Maths tutorial specifically on ratios. 😊