AS Biology - Student's t-test and Spearman's rank (OCR A Chapter 10.6)

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**Just spotted a mistake in my notes!**
For the "left hand side" of the critical value diagram, when t-value or Spearman's rank coefficient is LOWER than critical value at p=0.05, it should say:
"Therefore less than 95% confidence that there is significant difference or there is a correlation"
NOT "more than 95% confidence" which is the same as the one on the right...
I USED THE WRONG ARROW ON THE LEFT!!
So: my handwritten one is wrong, but my verbal explanation and the typed out example is CORRECT!
Sorry! :(
There are a few possible types of questions in exams on stats:
- Pick a statistical test to prove a certain point (so you'll need to know the purpose of each test)
- Calculate the actual value (use the equation given and be careful)
- Interpret the value in comparison to the critical value given in probability table
- Formulate a good conclusion.
The calculations aren't that bad if you're careful, so here we'll be focusing on how to interpret and structure a good conclusion to get the marks.
Please subscribe for more content and comment below to let me know what you think! :)
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16 май 2018

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Комментарии : 37

@BioRach 5 лет назад

***Just spotted a mistake in my notes!*** For the "left hand side" of the critical value diagram, when t-value or Spearman's rank coefficient is LOWER than critical value at p=0.05, it should say: "Therefore < 95% confidence that there is significant difference or there is a correlation" NOT "> 95% confidence" which is the same as the one on the right... I USED THE WRONG ARROW ON THE LEFT!! So: my handwritten one is wrong, but my verbal explanation and the typed out example is CORRECT! Sorry! :(

@sharfanc 2 года назад

Thank you for the clarification, but you needn't dread too much. I am certain that many have intercepted that error and corrected it of their own accord. Not only did we have the capacity to correct the mistake, bit it also proved to be an exercise for intellectual engagement- preventing your audience from erroneously copying down the information without genuine understanding of the content. Again, excellent explanation and clarity of information. Pursue your voyage to spread the dominion of knowledge!💯

@ayesha1929 2 года назад

@@sharfanc bro pulled out every high vocab word from the dictionary 💀💀...we get it...its not that deep...

@ishs7869 5 лет назад

Oh my goodness thank you so much!!, we had the most terrible biology teacher in year 12 that completely missed the biodiversity topic as well as others but you’re videos are really helping me to catch up ready for my exams🙏🙏

@BioRach 5 лет назад

Glad you find the videos helpful! :D Good luck with your revision and thanks for watching :)

@lycheemango3547 2 года назад

Please keep making these videos! They are the most amazing revision resources and really help some of the trickier topics the books tend to overcomplicate! We have plant hormones coming up soon and it's great to see you are still making these videos! Keep up the good work! :)

@slinkyneko 6 лет назад

This was super helpful! I wish my teachers could have explained it as well as you did. Thanks!

@BioRach 6 лет назад

Slinky Neko thanks for watching, glad you find it helpful! :)

@Crackheads305 3 года назад

You are really great. I just love your explanation ♥️

@LB-1234 Месяц назад

Thank you for making it so clear!

@malanhemal6574 2 года назад

Hi Biorach, What's the difference between an unpaired and paired t test?

@michelleokueguale3164 6 лет назад

Hi biorach i recently found your videos and I have to say they are really good and clear and straight to the point. Would you be able to make videos on the cardiac cycle Bohr shift transport of oxygen. Could you make a video dedicated to biodiversity in the new ocr a biology please thank you 😊

@BioRach 6 лет назад

Hi Michelle, thanks for watching and I'm very glad that you find them helpful! :) Unfortunately I may not be able to dash out more videos anytime soon (in case you're preparing for exams still), but these topics will be on the top of my list of topics to do!

@kiransandhu3415 Год назад

Hi Miss, I'm just going through these videos, and they are so helpful and to the point! Thanks for covering the content in an easy and understandable way! My teacher was right for recommending you! As I'm going through, I've noticed there isn't a 10.5 video? I was just wondering if you have a video for this part of the topic?

@BioRach Год назад

Glad that you found the videos helpful! :) No I haven't made a video for 10.5, since I've prioritised the topics that I think are the trickest for people, but will be making more videos this year to cover the gaps, so watch this space!

@danyah2629 3 года назад

i'm confused... how do you calculate the degrees of freedom for Spearman's rank?

@BioRach 3 года назад

Spearman's rank doesn't use degrees of freedom - you just refer to the data table and look for the p value from 'n', which is the number of pairs of data.

@justin-nx9jz Год назад

is this the same for chi squared? as my teacher said its flipped but I think he is wrong

@BioRach Год назад

Yes it is the same way to interpret chi squared. If the chi value is larger than the CV, then we are more than 95% sure there is significant difference between the observed and expected numbers. If less, then there is no significant difference, which usually implies there is epistasis or autosomal linkage involved (when using chi squared for genetics).

@chesskez7074 5 лет назад

So useful thankyouuuu

@BioRach 5 лет назад

Glad it's helpful! Thanks for watching :D

@kiransandhu3415 Год назад

will we ever have to work out the critical value?

@BioRach Год назад

You'll need to find the critical value using the data table given. So it's important to know how to work our the degree of freedom, so you can find the CV in the data table.

@tahirnanji 6 лет назад

lifesaver

@BioRach 6 лет назад

Thanks for watching! Glad you find them helpful :D

@apatchy0664 4 года назад

Is the critical value always 5%? I have no idea where to start with this - teaching myself in lockdown

@BioRach 4 года назад

Oof, tough one to self-teach this one! There are other critical values apart from the one at 5% (you can see them all in the critical value tables). However statisticians have decided that 95% certainty is the benchmark, hence we use the critical value at p = 0.05 Note that 95% confidence is 5% uncertainty. Actually in some exam Qs, you can use the CV at p = 0.01, where you're measuring it at a 99% benchmark. This will make your conclusion even more "precise", but we normally just set it at 95%. But I doubt you'll ever be asked to do so, the one Q I've seen that has the CV at p=0.01 is in its mark scheme, as alternative points that can be made, but not exclusively it.

@kairiannah 5 лет назад

cheers Rach

@BioRach 5 лет назад

no worries XD thanks for watching!

@malanhemal6574 2 года назад

Hi Biorach, I love your videos, but sometimes the things you say are cut. So, what you say is not fully heard. I thought it might helpful for me and other students who watch your videos. Love your videos, thank you ! Have a Great Day!

@zqgb Год назад

do we need to memorise the equations of Rs and t or is it given?

@BioRach Год назад

The equations will be provided. You do not need to memorise them.

@adamgrecula4498 Год назад

Hello Biorach, Amazing video but i would just like to ask, our biology teacher taught us that we aren't allowed to say that 'we accept the null hypothesis', but rather we should say 'we are unable to reject the null hypothesis'. I also study psychology and choosing statistical tests is also a common exam question and came up in 2/3 papers this year. I was taught for psychology that we say that 'we accept the null hypothesis'. I was wondering whether there is a significant difference (excuse the pun 😂) between these ways of saying that the null hypothesis is correct. Thank you for saving my biology exams!

@harrietjeffery750 Год назад

bit cringe mate x

@BioRach Год назад

It's absolutely fine to say "accept null hypothesis" in Biology - I haven't seen any past paper mark scheme that says otherwise! One thing to note though is that you should continue to elaborate on that point, so write a statement about the original hypothesis (e.g. we are more/less than 95% sure there is significant difference between A and B). Hope this helps! And I always appreciate Biology puns!! 😉