STATISTICS- Population VS Sample and it's Importance

Key Takeaways

[Music] hello all my name is Krishna and welcome to my youtube channel today we are going to be discuss a very important topic which is called as population and sample so let us go ahead and try to understand what is the agenda of this particular video so we will be discussing about what is population then we will try to understand what is sample now based on population and sample there is two more term which is called as population mean will understand the application of so also or application of population mean sample mean with an example so I am going to make you understand what is the population mean this is basically given by mu then I am going to make you understand what is exactly sample mean this is basically given by x-bar right and then I'm going to take a very good example to differentiate between population and sample in my next video I am also going to explain you about something called as random variables so let us go ahead and try to take a very simple example what exactly is population and sample and what is the difference between population mean and sample mean so let us go ahead so let us consider that I want to find out the average height of all the people in in in some particular state so suppose in this particular state they are around 1 million people they are around 1 million people and suppose I want to find out the average height right now with respect to this particular state it may be any state so they are basically 1 million people over here right now I'm going to revise the mean and mean formula also over here so if I want to find out the average height that basically means my formula will basically become 1 by 1 million multiplied by write summation of I is equal to 1 to 1 million right and then here I will basically be using my EXO Phi which is basically represented all these particular points where we are summing up and then we are doing an average of 1 million right over here this 1 million which is basically my total number of people in this particular state can be represented by capital n ok so my capital n over here is 1 million and because of that I have written summation of I is equal to 1 to capital M and I am basically finding out the average of basically all the 1 million people now just understand guys when I have this kind of problem statements like average height of all the people in a particular state it is very very difficult to go and actually find out the height of each and every person right because I can't like 1 million people are staying in this particular state I cannot go and ask what is the height of yours what is the height of I think it is it is very difficult to just calculate all those things so what do we do is that we basically use a new concept which is called as sample okay I'll just define what exactly sample so some suppose this is 1 million total from this what I will be doing is that we will be picking up some randomly 10,000 people okay from this suppose this is my sample and considering my sample population sorry basically my sample out of this particular population now out of this 1 million people I am just taking up a sample of 10,000 people now this 10,000 is basically denoted by small n okay now if I want to find out the average then what I can do is that I can basically write a formula I is equal to 1 to 10,000 right XOR 5 multiplied by 1 by 10,000 yes and not and and you know that we can collect some 10,000 data from this particular population itself I'll give a very good example where this population sample are heavily used ok and again guys when I want to find out this particular a ver egde this is denoted by X bar whereas this particular average which is my population mean so my population means is basically denoted by something called as mu whereas my sample mean is denoted by something called as x-bar okay so this can be considered X bar is equal to summation of I is equal to 1 to 10,000 X of I divided by 10,000 now what is the real use case of this why why we are learning about population and sample let's remember if you if if you have at least done one problem in machine learning problem statement you'll be seeing various data set right in that particular data set you'll be having some fixed number of Records you may be having 1 million records you may be having ten thousand records twenty thousand records and based on that you have to basically perform you have to basically apply some machine learning models to do the prediction now just imagine that ten thousand at twenty thousand that 1 million records are basically your sample from a particular population because it is very very difficult to collect all the data of the population okay so for that particular case what we do is that we just take sample of data and then we try to actually implement some machine learning algorithms let me give you a very good example I hope you have heard of something called as exit poll right so if you want to find out so suppose I'm just going to take an example ok if you if you want to find out which is the favorite party to win in this particular state right or you want to just find out the exit polling shot so I want to find out the exit poll after the election right and I want to see that how all the parties have basically performed ok now from this I cannot go to each and every person now I know that the my population in this state is 1 million people I cannot go and ask each and every person to which party did you vote so what does this news channel and other mediums do that they'll take a sample of chunk of population from every region ok suppose I am considering total number of people over here is selected as ten thousand this ten thousand will be selected equally or in an equal proportion from different different regions and this particular they'll basically record their answers and based on that and now this is mine sample and based on their answers based on their answers or output so based on their sorry based on the answers or input they will basically predict which party will win the election yes which party will basically win the election now not only this guys lot of surveys lot of exit poll surveys other kind of service you know based companies are going to go into the clients and customers to understand about the products it is not that they'll go to each and every person they'll just pick a sample of population then they'll try to ask that particular question and remember guys all of your data set in machine learning how many number of records they are basically a sample of data and you have to use that sample of data and basically create your own machine learning model prediction algorithms right so this is the importance of population and sample now some of the terms that you basically need to know if I want to represent the population count right suppose I want to represent the population count this is basically represented by capital M if I want to represent the sample count sample count basically means total number of values in this population or total number of values in the sample so that is what this count is basically specified so if I want to find out so if I were to represent something for the sample count this is represented by small n okay so capital n in small and if I want to find out if I want to represent what is the population mean this is represented by mu right if I want to represent sample mean this is represented by x-bar okay and you know about variance and standard deviation standard deviation is basically given by Sigma these are some of the notations that you basically use you know whenever you are actually working as a data science if whether you whenever you are working as a data analyst because this is the way you communicate with your team holders for them for making them understand about various terms and this is generic things that B that we basically use I hope you got the idea about population and sample I hope you understood it properly why we are you basically using this I've also give you given your very good practical location so this was all about this video video guys I hope you like this particular video please do subscribe the channel if you have not already subscribe share with all your friends I'll see y'all I'll see y'all in the next video have a great day ahead and one more surprise guys the next video that I'm going to make is something called as random variables I'm also going to discuss about the different types of random variables and again the main thing is that I'm going to take this term and include it in the terms of statistics and machine learning how that is basically implement how what is the main purpose of those in machine learning so I'll see you all in the next video have a great day thank you one at all [Music]