what is adjusted frequency ? why is it used ? please explain in detail.
Adjusted frequency of a class may be defined as the product of the frequency of corresponding class and the ratio of minimum class size to the class size.
We use the concept of adjusted frequency distribution to draw histogram of the class intervals of different width. Using it the frequency of the class intervals are adjusted in order to make the frequencies of the each class intervals and the area of the corresponding bar representing the histogram of class intervals in equal proportion.
Its use arises from the following condition:
Consider a data having class intervals are 0 – 5, 5 – 10, 10 – 20, 20 – 40, 40 – 50, and
50 – 80.
Now, each class interval is continuous as there is no gap between the consecutive class intervals.
Here, the class intervals do not have uniform class size as the class size of the class interval 0 – 5 is 5, whereas the class size of the class interval 10 – 20 is 10 which suggest that the class size isn't uniform which will result in non-uniform graph. So, the frequency is adjusted so as to maintain a constant area of the rectangle formed by joining the mid-points of the bars of the histogram or for the construction of a histogram of a continuos grouped frequency distribution with unequal class intervals.
To know how it works please go through the video mentioned in the link provided below.