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Normality test [Simply Explained]
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- Опубліковано 18 сер 2024
- One of the most common requirements for statistical test procedures is that the data used must be normally distributed. For example, if a t-test or an ANOVA is to be calculated, it must first be tested whether the data or variables are normally distributed. This is done with a test of normality.
If the normal distribution of the data is not given, the above procedures cannot be used and the non-parametric tests, which do not require normal distribution of the data, must be used.
How do I test normal distribution?
Normal distribution can be tested either analytically or graphically. The most common analytical tests to check data for normal distribution are the:
1) Kolmogorov-Smirnov Test
2) Shapiro-Wilk Test
3) Anderson-Darling Test
For the graphical test either a histogram or the Q-Q plot is used. Q-Q stands for Quantile Quantile Plot, it compares the actual observed distribution and the expected theoretical distribution.
Normality test
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Wonderful! Many many thanks for your nice feedback!!!! Regards Hannah
after several months of search for the best videos , finally i found ...thank you so much for such a wonderful videos..
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unbelievable, what kind of presentation this is
THANK YOU SO MUCH. Your videos are very insightful and simplified to be understood
You're very welcome! Many thanks for your nice Feedback! Regards Hannah
00:02 The video explains testing for normality.
01:00 Normality tests check if data fits a normal distribution
01:56 P-value and normal distribution
02:50 Normality tests help to check distribution types
03:52 Large sample size can lead to rejecting the assumption of normal distribution based on small p-values.
04:53 Use QQ plot for better assessment of normality
05:49 Using data tab for testing normal distribution
06:52 Understanding the importance of normality test in data analysis
Crafted by Merlin AI.
Great explanation on Normal Distribution!
You are one of the best teacher
Many thanks!!!!
Can I ask a question about normal distribution as part of the assumptions in ANOVA please? Are we looking at normal distribution for the whole set of data or for each independent variable group?
Say we're doing a one way ANOVA without repeated measures and we have 3 groups (A, B, C) who had one dependent variable measure (weight). Should we run normality test for each of A, B, and C ?
Thank you
Such a life saver explanation 😍❤
Thanks a lot.
Glad it was helpful and many thanks for the Feedback! Regards Hannah
Wonderful teaching !
Many thanks!
youre better than my teacher omg thank you
Good work, clear explanation
Very nice explanation you have done with DATAtab. I need to know how it can be done in Excel sheet.
Thanks for your nice feedback! : )
What are the two visual methods that the presenter mentions?
What is the degree of freedom in Shapiro-Wilk test ?
Hi the concept of "degrees of freedom" as commonly discussed in statistics (e.g., in the context of a t-test or chi-squared test) isn't directly applicable to the Shapiro-Wilk test in the same way. The Shapiro-Wilk test doesn't yield a "degrees of freedom" value like some other statistical tests.
Instead, the test involves computing the W statistic based on the observed data and expected values under a normal distribution. The critical value to which you compare the W statistic depends on the sample size, and tables or software often provide these critical values for various significance levels and sample sizes.
Regards,
Hannah
thank you so much
You're welcome!
Herzlichen Dank
Gerne : ) LG Hannah
What to do when normality test is positive for one parameter and negative for other parameter .
Then you look at the graphical solution and decide with best conscience. It is best if you also mention it in your research!
@@datatab thank you
i have question. i have done 2 research hyphotheis and their normaality tests.For eg i have said ho the perceivness . bout social media follows normal and h1 follows not normal.My test shows both my objectives are not normally distributed .so how to interprete in disccussion chapter and conlunsion
Instead of obtained score can normal distribution test be applied on likert response?
Good job
Many Thanks : ) Regards, Hannah
Thanks, great job
You're welcome and thanks for the nice feedback! Regards, Hannah
Thanx ❤
I love you guys ❤
We should do this for all kind of study like crosectional study?
For data that is collected in a Likert Scale, won't the data always violate the normality assumption? Because, the likert scale takes discrete values.
What accent it is?
wow mam well explaniation about normalilty test, but I have question that for analitical method we have a threshold of 0.05 i.e if results are less than 0.05 we can say that data is not normal and vice versa, but for graphical method what if the data is near to normal distribnution, that when we can cofidently say that our data is normal or not. just like a fix threshold value of p in analytical method.
Thank you so much😍
You're welcome 😊
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Thanks : )
🎉🎉🎉🎉wow