Statistics-Finding Outliers in Dataset using Z- score and IQR

Рет қаралды 86,792

4 жыл бұрын

In this video we will understand how we can find an outlier in a dataset using python.
#Z-Score
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Пікірлер: 79

@satyaprakash5905 4 жыл бұрын

Z-Score & Outliers - explained in very easy way. Thank you..

@prathameshjoshi1408 4 жыл бұрын

Thank You so much for explaining most of the concepts in simplest way.When you explain anything by far anyone can say you really want us ( your students ) to learn more . One of the best teachers for sure. Thankyou and best of luck for further success on KZfaq.

@ayushijmusic 3 жыл бұрын

Best!!! Thankyou! This channel is a saviour in DS doubts

@shivambhayre5056 4 жыл бұрын

Thanx bro mujhe ye sb pta tha i mean pure theory and formulas but implement kese krte h python me ye tumne bahut easy way me explain kia thanx man really appreciate that and me wait krunga agle video ka jisme real data p kre thanx for that because me R p ye kr leta hu but i am not good in python aur tum bahut sahi tarike se smjhate ho thnx for that🙏

@safwanmansuri792 4 жыл бұрын

You continue this hardwork ,surely you will get success one day on KZfaq.

@vsabinat 2 жыл бұрын

Wonderfully explained. Won't forget now. Thank you

@shashankverma4044 4 жыл бұрын

Thank you so much ...Concept cleared perfectly:)

@idanamayank 4 жыл бұрын

Simply awesome,great work

@sandipansarkar9211 3 жыл бұрын

Awesome explanation Krish.Thanks

@justfun6409 2 жыл бұрын

Could you please arrange the playlist videos in 1st to last manner? Just I am getting confused that which video I should watch after particular video. By the way, you explain very well👍🏻💥

@mannudhapola1210 4 жыл бұрын

Smoothly explained

@rambaldotra2221 3 жыл бұрын

Thanks a Lot Sir, Really helpful.

@sudiptachakraborty745 4 жыл бұрын

Sir - I appreciate your effort of making all these beautiful videos. It makes life easy for all of us. But I need to make one comment on this video, at the beginning you said when the weight(x) is increasing height(y) is also increasing but in real world if you think it's not possible right ? As per my thought process may be you wanted to say when the height(x) is increasing weight(y) is also in a increasing trend. In most of the cases, when a person's height increases automatically weight also get increased but it's not the reverse. I hope i am making sense here. Thank you once again :)

@baharehghanbarikondori1965 3 жыл бұрын

amazing tutorial, thank you

@yendamurikrishnavamsi3188 3 жыл бұрын

super!!! well explained sir!!!!!

@kadhirn4792 4 жыл бұрын

Damn good dude. Thank you so much.

@ty_b_63_prajwalwaykos86 2 жыл бұрын

Hi Krish, its always great to learn from you... can anyone please tell when to use what? Or which amonthe the methds is best? or is it case wise and if yes what are the cases?

@shivambhayre5056 4 жыл бұрын

If we have many outliers, in that case, is it good to calculate(or detect by frequency)mode over mean and median ?? And then replace them with mode (mostly we do it for categorical variables) is this a good way?????

@harshtamkiya8505 4 жыл бұрын

Nice explanation..

@balajivarma83 4 жыл бұрын

Sir please upload you kaggle competition of house price with feature selection. Waiting for your vedio

@louerleseigneur4532 3 жыл бұрын

Thanks Krish

@ele_wings7521 4 жыл бұрын

thanks alot... sir..

@AkshaySharma-vm9sp 4 жыл бұрын

Sir please make video on p value

@umesh789s 4 жыл бұрын

This was really explained very well. I have a doubt regarding multipication by 1.5 , can you please elaborate how this 1.5 came or what is the method by which we can get this value in any other dataset.

@umesh789s 4 жыл бұрын

Now i can breifly explain why only 1.5 and the reason is really amazing and really informative.

@KumarGolu2001 4 жыл бұрын

Can you explain me ?

@lokeshkaturi4040 3 жыл бұрын

@@KumarGolu2001 It is just a proof done by stats people , 1.5 gave the right bound values to detect outliers.

@pranjalmittal7475 4 жыл бұрын

sir please upload video on preprocessing data using sklearn library

@rohitsharma-kr9gk 4 жыл бұрын

Sir can you make a video on fitness based recommendation system. and can you tell me how to collect data set of different people and recommend them food and exercise according to that data set. plz reply sir....

@samitaadhikari3182 3 жыл бұрын

actually that is very good idea i hope you learned that i'm gonna try this once i learned this

@pawansonu41 2 жыл бұрын

at 14:13 point 4 and point 5 are wrong..however in code you have implemented correctly. A suggestion please "try to keep formulas and notes clean, because if that is ruined whole plot gets off". Though you have done a good job by far.

@TheTimtimtimtam 4 жыл бұрын

Nice

@rahulgarg6363 3 жыл бұрын

perfectly explained krish but How to detect outliers for multidimensional data

@903vishnu 3 жыл бұрын

If there are more number of features (like X1 X2 X3 and so on) then how can we find out using Scotter plot

@abishekkachroo938 4 жыл бұрын

I am facing a unique issue , following this methdology for IQR: Mine lower value of column is coming . Below is the pseudo Code: Q1 = df[' shares'].quantile(0.25) Q3 = df[' shares'].quantile(0.75) IQR = Q3 - Q1 low = Q1 - 1.5 * IQR ------>>>>>>>>> this value is coming extreme negative which is not even present in columns The problem maybe is IQR value > Q1. How to solve ? Shall I change the % age?

@akshatabm4491 9 ай бұрын

Is the detect_outlier using z score program working fine for everyone?? It is not returning correct output for a diff dataset used.

@umesh789s 4 жыл бұрын

I am not able to find the link of the next video which you have told related to outlier handling in a dataset from kaggle.

@KumarGolu2001 4 жыл бұрын

I also not getting the video

@meenadalvi9743 4 жыл бұрын

In the detect outlier function "y" is not defined anywhere please change it to i

@prateshtamhankar3568 3 жыл бұрын

we can use any one of the technique 1.Z-score or 2.IQR to find outliers??

@niveditaparab6772 3 жыл бұрын

generally when data is skewed IQR better if roughly normal then z score better

@sheelstera Жыл бұрын

Standard Normal distribution can be applied only to a normally distributed column...SND applied to a non-normally distributed column may give you a mean of 0 and and SD = 1 but the nature of distribution is still non-normal. Z score cannot be directly tied to the 99.7% of ND in such a case. The interpretation of Z score is therefore subject to the kind of the distribution structure of the column which remains unaltered before and after the Standardization process.

@mohammedyahya39 3 жыл бұрын

Hi Krish, I have a doubt regarding the parameter inside the function , when defining the function ...it is given as data. It should be the dataset right ?

@shantomatt 3 жыл бұрын

data is just the parameter name , can be any label

@ukquaratine1019 3 жыл бұрын

can the value of inter quantile would be range in negative(-)

@ash_engineering 4 жыл бұрын

Sir how is this method scalable when we have 50s or 100s of dimension /features in a dataset

@anirudhyadav-mq8nd 4 жыл бұрын

IQR method can be used when the data is huge

@shahzan525 3 жыл бұрын

i couldn't find the next video which you talk about in the last....

@janardanpandey6942 2 жыл бұрын

Here outliers is exactly coming in Z score when I'm putting the value of threshold=1 and not coming when putting the value of threshold=3 WHY????? Btw thaxx alot very outstanding playlist for STATISTICS.....Gtr work

@vicky-do5th 3 жыл бұрын

sir why you have taken threshold as 3 as you said it should fall in 3rd standard deviation ,so it should not be (3*std)?

@namansharma9697 3 жыл бұрын

how can mean be equal to zero in real-time scenario as weight cannot be assigned a negative value please help

@knavk1 3 жыл бұрын

Hi.. How to work with outliers.. I don't want to remove outliers from my data. Is there a way which I can do that?

@cvb6931 3 жыл бұрын

I have few doubts... why threshold value is considered as 3 I have seen other examples they also considering as 3 only ? is it always 3 ? why to only multiply with 1.5 for lower and upper bound values ... any specific reason? Does iQR works on categorical columns also ... I know that zscore doesn't work for categorical values?

@ty_b_63_prajwalwaykos86 2 жыл бұрын

Answering your doubts--- 1. it is not really 3 actually it is 3*sd where sd is 1(since by using z-score we make the normal distribution with mean=0 and sd =1) and yes, we always take the 3rd sd. that is all the values which are beyond 3rd sd are outliers. because until we reach 3rd sd 99.7% values are covered. which seems pretty enough. 2. As krish stated 1.5 is a statistical figure and drawn out of experiments so basically we have to use it. 3. It is very obvious ....using such statistics on categorical data doesn't make any sense. If you still not get it. just tell me how exactly are you going to sort categorical values at the first place😅😂😂🤣

@anchitbhushan6172 4 жыл бұрын

So which one should we use for removing the outliers??

@lokeshkaturi4040 3 жыл бұрын

Exploring all the ways is the best thing.

@akankshagupta5067 4 жыл бұрын

In your code, after are np.abs(z_score) > threshold: Why are you appending y?? Shouldn't you append i?? Please correct it as it is misleading.

@lifeisfun9 4 жыл бұрын

Sir. Firstly a brilliant teaching and mentor. I have some doubt in calculating upper bound and lower bound you showed. You are saying anything beyond 1.5iqr will be outlier, then why we are doing low= q1-1.5iqr and high=q3+1.5iqr. cant we straight away get outliers by comapring if number is less than or greater than 1.5iqr. I did not understand meaning of q1-1.5iqr as lower bound and similarly for upper bound. How?

@lifeisfun9 4 жыл бұрын

Oh I understood . I read the text later. Thankyou so much for sharing your knowledge

@Joshua75623 4 жыл бұрын

Akansha, did you got the answer for your question? Even Im getting the same doubt

@BehindTheLogics 4 жыл бұрын

@@Joshua75623 First the values are sorted in increasing order. Q1 is the 25th percentile, Q3 is the 75th percentile. IQR is the length of the box. so values > Q3+1.5times IQR and values < Q1+1.5times IQR indicates the outlier.

@indirajithkv7793 2 жыл бұрын

❤💫

@nayazithousifkhan1696 4 жыл бұрын

Post the video of box plot technique

@BehindTheLogics 4 жыл бұрын

@nayazi kzfaq.info/get/bejne/ebyUltWQsqmWe4k.html Watch this video from 6.25

@shantomatt 3 жыл бұрын

plt.boxplot(x=dataset)

@forammodi5850 3 жыл бұрын

Sir i got error name error Nameerror: name mean is not defined

@srinathganesh6985 3 жыл бұрын

can categorical data (encoded) have outliers?

@lokeshkaturi4040 3 жыл бұрын

Here is a nice explanation about how to detect outliers on categorical data .

@dreamday4810 2 жыл бұрын

@@lokeshkaturi4040 can you please share timestamp in this video

@tammy4994 3 жыл бұрын

how he has set threshold as 3?

@Daily_Dose_Of_Life 3 жыл бұрын

Thank you, sir Finding Outliers with help of Z Score Using Pandas: Just some modifications outliers=[] def detect_outliers(df): threshold=3 # 3 standard deviations # mean=np.mean(df) #std=np.std(df) z_score=(df-df.mean())/df.std() df['out']=z_score[z_score>threshold] df.dropna(inplace=True) return df.iloc[:,0].values.tolist() detect_outliers(d)

@sandipanpaul1994 4 жыл бұрын

@krish why it is only 1.5 . Why not 1 or 2. Why only 1.5

@amalsunil4722 4 жыл бұрын

it's proven mathematically comparing with the standard normal distribution ....actually it's 1.7 but it's taken to be 1.5 for 'symmetry'

@TechBinod 4 жыл бұрын

Your video is great but not systemically managed

@rajprajapati888 2 жыл бұрын

Z-score isn't give output for more than 3 outliers

@maithreshpalemkota 2 жыл бұрын

It is more appropriate to call it Quartile than calling them Quantile.

@ashwinimandani2829 4 жыл бұрын

Sir, I tried finding the outliers in a dataset using both methods(Z-Score,IQR) and the answers are different. Can you please explain why?

@amalsunil4722 4 жыл бұрын

yea that happens....cuz mathematically proven: 1.7 is the accurate measure for the length of whiskers but it's taken as 1.5 for "symmetry". So you may check with 1.7 instead of 1.5 and observe the same result for z-score and iqr