For A level biology the T test is all that is needed and its not necessary to use a Z test. But the T test will be an estimate of the population mean e.g. mean of 20 leaves from a tree is not the mean of all the leaves from the tree. Z test would use all the leaves from the tree for the mean.
@@alevelbiologymrashcroft8177 From the above-mentioned book "When both sample sizes are high ( >30) a z test is used as an alternative to a t test" - I know I am picking hairs, but even though this is "only" A level, it might be handy to have the explanation that although this is not the t test it can be used as such. It's so very confusing especially when faced with so many varying formulae (although that may be because I went from GCSE to degree as a mature student so missed out on the in between knowledge). Saying that this is a very informative video.
With the one tailed test we are looking at any significant change in one direction , so here is would be significantly wider leaves in light vs width of leaves in shade. So P
Priyadharsshine Sekar the critical value is always set at a given degrees of freedom (number of values in data set 1 + number of values in data set 2 minus 2).. find the critical value from the table at whatever p value you want to test against, this is normally set at p=0.05. So you will have a critical value set at this p value. You could have a critical value from the table set at p0.01 if you want. Now compare the t value to the critical value from the table set at your p value of choice... if the t value is bigger than that critical value, then the P value is smaller than that p value for example set at P=0.05, so you would write P
No. Don't take out any values. The point of using the mean and the SD of each data set is they use all of the values measured. If you start to take out data points it biases the data/result. The SD will allow you to identify that there is an anomaly or that not all values are close to the mean value.
No this is the correct formula. Some say “variance” in the equation but this is just SD squared as we have. You need the two means and the two SD to calculate the T value using the equation.
@@alevelbiologymrashcroft8177 okay sir. Been watching some videos lately, but I came across that there are different T test (random sample), (two samples independent samples), (two samples dependent samples), (two samples dependent samples) and testing the significance of an observed correlation coefficient. Your T test samples belong to which which one of the above?
@@jasonkambuli this is a independent two sample T test where you look for any significant difference between two means of unrelated groups . E.g mean width leaves from plants in light vs leaves from plants in dark. A paired T test might be. For example, comparing one mean (start of a drug trial) with the mean at the end of the drug trial for the same group of people. How the mean has changed over time.
the calmness....the composure.....the time put into this.....mate you deserve my gratitude.....THANK YOU
This the best, video, in the history of explaining the T test, bravo my guy,
The likes on this vid don't do it justice. Literally the best video on t test on this platform. Thank you so much.😍😍😍
This is the best explanation ever on the T-TEST ...Thanks very much 🙂🙂🙏🙏💥
This was the best explanation of the T-test on RUclips. Thank you for this. Big like and subscribe from me!
I second you
And so here Ladies and Gentlemen we witness the teaching of a legend
Amazing man! amazing explanation, your this video helped me a lot in my research work, thanks
Thank you very much! Much better than my stat teacher!
Great job! Helped me a lot... Thank you so much.
i like your way presentingdata,
thankyou
thank u so much
Beautifully explained Sir!
Great job, Thanks 🌷
Why did you calculate twice for the standard deviation quare dividing with the n. And y did you use the n of 15 instead of 14
According to Using Statistics to Understand the Environment by C Wheater and Penny Cook (pg 74, box 4.2), this is the Z test, not the t test
For A level biology the T test is all that is needed and its not necessary to use a Z test. But the T test will be an estimate of the population mean e.g. mean of 20 leaves from a tree is not the mean of all the leaves from the tree. Z test would use all the leaves from the tree for the mean.
@@alevelbiologymrashcroft8177 From the above-mentioned book "When both sample sizes are high ( >30) a z test is used as an alternative to a t test" - I know I am picking hairs, but even though this is "only" A level, it might be handy to have the explanation that although this is not the t test it can be used as such. It's so very confusing especially when faced with so many varying formulae (although that may be because I went from GCSE to degree as a mature student so missed out on the in between knowledge). Saying that this is a very informative video.
when sample size(15=n)
thank you sir.
Nice
If the channel had a playlist of the series
can you explain please why you did not consider it as a two tale test and divided the 0.05/2 in this sample
With the one tailed test we are looking at any significant change in one direction , so here is would be significantly wider leaves in light vs width of leaves in shade. So P
Could u explain how to explain how the difference in p value is related to critical value
Priyadharsshine Sekar the critical value is always set at a given degrees of freedom (number of values in data set 1 + number of values in data set 2 minus 2).. find the critical value from the table at whatever p value you want to test against, this is normally set at p=0.05. So you will have a critical value set at this p value. You could have a critical value from the table set at p0.01 if you want. Now compare the t value to the critical value from the table set at your p value of choice... if the t value is bigger than that critical value, then the P value is smaller than that p value for example set at P=0.05, so you would write P
Big thanks
13:19 in sample 1, leaf number 14 isn't there an anomaly which you wouldn't take into account for the mean??
No. Don't take out any values. The point of using the mean and the SD of each data set is they use all of the values measured. If you start to take out data points it biases the data/result. The SD will allow you to identify that there is an anomaly or that not all values are close to the mean value.
A level Biology: Mr Ashcroft oh right thanks. Do you have any other statistics videos
Are there two formula to calculate the T TEST? Am seeing other videos are using different formula.
No this is the correct formula. Some say “variance” in the equation but this is just SD squared as we have. You need the two means and the two SD to calculate the T value using the equation.
@@alevelbiologymrashcroft8177 okay sir. Been watching some videos lately, but I came across that there are different T test (random sample), (two samples independent samples), (two samples dependent samples), (two samples dependent samples) and testing the significance of an observed correlation coefficient.
Your T test samples belong to which which one of the above?
@@jasonkambuli this is a independent two sample T test where you look for any significant difference between two means of unrelated groups . E.g mean width leaves from plants in light vs leaves from plants in dark. A paired T test might be. For example, comparing one mean (start of a drug trial) with the mean at the end of the drug trial for the same group of people. How the mean has changed over time.
www.sthda.com/english/wiki/t-test-formula
@@alevelbiologymrashcroft8177 thank you. Does it means that if it’s dependent two sample T test the formula has to change?
Isn't this f test
we don't accept the null hypothesis, we fail to reject it.
For the benefit of A level students and getting marks in exams.. null is either accepted or rejected (marking points) 👍
@@alevelbiologymrashcroft8177 got it
@@alevelbiologymrashcroft8177 thanks for the video btw
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