Histogram

General Idea behind a histogram is to divide the dataset into groups of equal length , Which allows us to see the patterns in the data instead of details information , we would get from what is basically a list of numbers.

In the histogram of salaries above those groups are 24-32,32-40,...and so on. Once the group has been chosen , the frequency of each group is determined.

The frequency is simply the number of data values that are in each group.

Let's look at the very first group 24-32 , the bar goes up to 6 , means that this group has a frequency of 6 ; 6 employee have salary in between 24 and 32 , but 32 is not included.

If we have list of all the salaries between 24 and 32 thousand , In otherwords , 6 people in this group made salary between $24000 and $32000.

Note:

- A group 24-32 , doesn't include the 32 thousand , that groups accept value from 24 thousand and 31 thousand but not 32.
- detail conclusion , while we can say most of people in this group made less than $50 , that's where most frequency is. and we couldn't use this graph to say how many people made exact salary $35000 or how many made exact $50000.


In histogram we will "lose" the information about individual data values when we group the data.If we didn't want to lose that information we may choose to use a dotplot or a steam plot to display the data instead of histo.