Quantitative data is numerical values. These can either be continuous such as the weight of a mass or discrete such as the number of children in a family.

An effective way to represent quantitative data is through a histogram.

On the x axis are the class intervals. The area of each block represents the % of people in that class interval. The height of each box represents the % in the block divided by the length of the class interval. Hence the higher the block the more crowded it is.

Box plots are another way of representing data. These show the median, the interquartile range and the outliers. Hence these are useful for comparing data sets.

You can create a comparative box plot to compare data which has a quantitative variable and qualitative variable.

Scatter plots are used for comparing two variables in order to determine a trend between them.