Hello dear students, we are discussing about time series. Time series first method is over, free hand method. Second one is here, method of semi averages. This is one of the very important and easy to understand logic you have to understand.
understand this is also graphical method method of semi average semi average we are going to calculate so this is quite easy through a problem will work out and you can understand it quite easily so now here the problem is given given fit a trend value fit a trend value for the following data using the method of semi-average by using semi-average method we have to fit or we have to draw trend line same like previous problem actual line will be there trend line will be there both we have to draw it in graph so what is given to us year 1991 to 96 91 92 93 94 95 96 six years average we have to calculate first so for that what is given to us sales sales of the six year sales it's in thousand units what we have to do is first calculate the average semi average means we'll make it half of this data six data so what we can do we can make it three three three three and we'll calculate the average of the three years I have done this here you can see here six years sales six sales are there We will make it half. Semi average means we have to take it half. So for this first 3 years 20, 24, 22. This average I have taken. Average how do you take?
Total up 20, 24, 22. If you total up you will get 66. 66 divided by 3. So that you are getting 22. 22 is the average of these 3 years. In the next 3 years 30 plus 28 plus 32. it is 90 90 divided by 3 you are getting 30 this is another average two averages we got first year average 22 second year average 30 just to keep it with you first we'll draw freehand line then after actual line that is actual line then after that we'll plot this too so before going to the problem we have to write or after drawing this you have to give a note so that note tell you end of this problem so that you have to mention it now coming to this problem I have taken on the x-axis x-axis year y-axis taken sales X axis years, how many years? 3 years.
91, 92, 93, 94, 95, 96. 6 years are plotted. On the Y axis, if you see the sales, minimum is here 20, maximum is 30. So in between. So I am taking here class interval of 10. Started with 10, 20, 30, 40. 40 is maximum.
Actually 30 only. So anyway as per the class interval I have taken extra little bit. So return. class interval of 10 with that and 20 30 40 on the y-axis sales so first we'll go for actual line actual line so 91 is here 20 91 is 20 this is 92 is 24 see here 93 is 22 22 means it's here next 94 30 95 is 28, 26 is 30. So, this is actual one. Let us join.
This is actual. Now trend we have to. So for trend what we have to do?
Semi-average they are saying. Semi-average means we have already taken two averages 22 and 30. So this we have to plot. Where we have to plot? 22 it is the average of 91, 92, 93. so we'll take 22 at 92 middle average average will be taking for the middle year middle year is 92 92 we are going to plot 22 in the same way 30 what is a middle year of this 30 95 at 95 we are going to plot we are going to identify 30 okay are you getting it's how you got it 92 is the average year of this three that that actual value is 22 and 95 is the average value of the downside average year value is 30. we'll plot that 92 22 92 is here 22 means it's here next one 95 30 95 30. two we have plotted now we'll draw one line trend line by adding these two semi averages it's like this this is trend line is it going in between the lines this is actually is it going in between the lines actual lines yes it is going so it is downside upside and it's going in between that so this is perfect you can say but always remember you have to give a note as ears are given 6 you can write down the note down side slowly you can write down as it has given in the problem 6 years six years average we are taking into two years two averages we are taking first three years average is 22 and subsequently the rest of the three years average is 30 so we are going to plot 30 sorry 22 and 30 as a trend line in the graph can write that note And after that, this graph.
Enough. That's it. So this is, we call it as a semi-average. Semi-average is simple.
What we have done is here, actual one is, we know, we have plotted actual one. And semi-average, how many years are given? Make it half.
First half average, second half average. As we have done. So that we are going to plot.
If at all 7 years are given, odd number, then we leave the middle number, taking the average of us. three second three and as we got it will plot it this is semi average simple and easy to understand easy to follow right so next we'll go for the other methods also so before going to other methods please check the description box lot of subject lot of links are given and different topics which may be useful for you and if you got confusion like I want break-even point topic whether I have covered or not want to know simply you can you can type it in the on the the YouTube Devi Kabat Nag break even point you will get that link or in description box or playlist if you go also you will get that link so this is the right way and easy way to find out the topic or subject so practice well issue good luck