i)a quantity having a numerical value for each member of a group, especially one whose values occur according to a frequency distribution
ii)the size of each class into which a range of a variable is divided, as represented by the divisions of a histogram or bar chart.
Class Mark (Midpoint) The number in the middle of theclass. It is found by adding the upper and lower limits and dividing by two. It can also be found by adding the upper and lower boundaries and dividing by two.
The lower class limit of a class is the smallest data value that can go into the class. The upper class limit of a class is the largest data value that can go into the class. Class limits have the same accuracy as the data values; the same number of decimal places as the data values.
In exclusive form, the lower and upper limits are known as true lower limit and trueupper limit of the class interval. Thus, class limits of 10 - 20 class intervals in the exclusive form are 10 and 20. ● In inclusive form, class limits are obtained by subtracting 0.5 from lower limitand adding 0.5 to the upper limit.
The frequency of a group (or class interval) is the number of data values that fall in the range specified by that group (or class interval).