Finding Outliers using Interquartile Range | Statistics, IQR, Quartiles

How do we find outliers of a data set using the interquartile range? This is done using a simple rule, any value less than Q1-1.5*IQR is an outlier, and any value greater than Q3+1.5*IQR is an outlier. We'll go through the step by step process of finding outliers using IQR in today's video statistics lesson! #Statistics #APStats

Remember that a data value being an outlier doesn't suggest we should discard it; it means we should take a close look at it and decide what to do in our statistical analysis. We may want to discard it, it may be an error/typo in which case we would want to correct it if possible, or it may be a key to understanding the situation being analyzed!

Also, remember that if this rule doesn't identify a value as an outlier - that doesn't mean YOU don't think it is an outlier. If a data set is sufficiently small you can look at each value individually and determine what values merit special attention. This rule for outliers is particularly useful for large data sets; but we apply it to small data sets so we can practice applying it by hand and seeing it in action!

I hope you find this video helpful, and be sure to ask any questions down in the comments!

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The outro music is by a favorite musician of mine named Vallow, who, upon my request, kindly gave me permission to use his music in my outros. I usually put my own music in the outros, but I love Vallow's music, and wanted to share it with those of you watching. Please check out all of his wonderful work.

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[zyphorx]

Thank you so much for this clarification! Helped me study for my RS1 progress check.

[inna]

Thank you so much for your SIMPLE AND DETAILED explanation! I understand the topic better now!!

[tinni]

Hey...thanks for the explanation. Could you elaborate on the "1.5"? Any particular reason for this formula?

[HICHAMELKHOU-st]

omg thank you so much your explanations are amazing, i understood it so fast!!

[nargiskhan]

This was so helpful, Keep up the good work. Thank You.

[nisritidris-said]

Thank you so much! btw I thought this was Sheldon from big bang explaining while watching.

[tivemajoroh]

Hey thanks for this! I was just wondering what if the two numbers are the same when calculating the median ? E, g 1, 2, 3, 3, 4, 5 if the median is still 3 would I still include the other 3s in my first and third quartile ?

[saemonne]

just too clear, been giving me hard time but after this video, its cool

[superslim]

Thanks. However, what happens if I use 1/4(N+1)th value to find Q1, which gives 66 instead of 67? Could you kindly explain?

[shadifm]

Thanks for explanation. Is it possible to not find any outliers in our data?! Because i did a test through this way and i didn’t have any value less than my lower bound and even not value greater than upper bound!

[Wedgeman_Riley]

when your doing your A-levels and have to come back to the basics