Sir thank you so much for this literally took only 5 minutes to understand with this ! Just one thing I need to ask you though I think While calculating standard deviation we take denominator as N instead of N-1 ?🤔
Hi Seema, "N" is used on its own when calculating for a population. We use "n-1" when calculating standard deviation because we are using a sample. Dr E.
Hi Marilyn, The alpha value is set by the researcher conducting the test. Usually this is done before running the test. All tests like this involve uncertainty - this is because we are using a small sample to make an inference about a larger population. The alpha value tells us what level of uncertainty you are going to work with. For example, setting alpha at 0.05 means that we will be 95% confident in our result. Hope this helps, Dr E.
Hi +jbeddiejb, The calculations will always be the same, ie - you will get the same z score no matter what your hypothesis is. It is therefore vitally important that you get the null and alternate hypotheses correct, otherwise you might make the wrong decision. Dr E.
The Z-test is designed for samples where the standard deviation of the hypothesized population is already known. It is commonly conducted for sample sizes of 30 or larger because, in such cases, the sample standard deviation closely approximates the population standard deviation. However, if the population standard deviation is already known, the sample size doesn't matter, even if it's less than 30, because you're not using the sample standard deviation to estimate the population standard deviation-you already know it.
Your videos are the only ones I seem to understand. Thank you so much!
From where you get z critical value "-1.645 ". Please tell.
sir, how do we get the interval for Z=-1.665 to 1.665 for comparing -2.51?
Thanks for this Eugene, this is handy to know how complete manually without an over-reliance on Excel (as wonderful as Excel is)
This is really helpful. please do u have a video on t test
I'm here coz of my course, we'll be making a java program about it x
sir ...I need ur lecture for factor analysis
Sir thank you so much for this literally took only 5 minutes to understand with this !
Just one thing I need to ask you though
I think While calculating standard deviation we take denominator as N instead of N-1 ?🤔
Hi Seema,
"N" is used on its own when calculating for a population. We use "n-1" when calculating standard deviation because we are using a sample.
Dr E.
Can you please explain where you got the alpha value from?
Hi Marilyn,
The alpha value is set by the researcher conducting the test. Usually this is done before running the test. All tests like this involve uncertainty - this is because we are using a small sample to make an inference about a larger population. The alpha value tells us what level of uncertainty you are going to work with. For example, setting alpha at 0.05 means that we will be 95% confident in our result.
Hope this helps,
Dr E.
What would you change if you set your null hypothesis to be 1000. Would anything change in the calculations?
Hi +jbeddiejb,
The calculations will always be the same, ie - you will get the same z score no matter what your hypothesis is. It is therefore vitally important that you get the null and alternate hypotheses correct, otherwise you might make the wrong decision.
Dr E.
Please help. How did you get the boundaries z= 1.645 and -1.645
Hi Oenone,
These values are taken from Statistics tables. They have been worked out by statisticians for us to use.
Dr E.
How is 0.05 alpha? How did you get that number?
0.05 is equal to 5 % which is equivalent to 95% confidence level.
Why didn't you use a t-score table instead? Because the sample size is less than 30.
The Z-test is designed for samples where the standard deviation of the hypothesized population is already known. It is commonly conducted for sample sizes of 30 or larger because, in such cases, the sample standard deviation closely approximates the population standard deviation. However, if the population standard deviation is already known, the sample size doesn't matter, even if it's less than 30, because you're not using the sample standard deviation to estimate the population standard deviation-you already know it.
@@SoumyashreeGhorai Thank you for the assistance! Good work.
Your calculated value "-2.51" is greater than critical value "-1.645". But how it is still in rejection region.
this not z-score it is z-test
Thank you uncie Euge! :D
+Maeve O'Loughlin - Subscribe to my channel to get updates - more (by hand) videos coming!
E.