l value = Size of = th value = . D = Size of N th b ] g l value = Size of = . th value = . P = Size of N th g l value = Size of = .
th value = . (iii) Grouped data (Continuous case): In the case of continuous frequency distribution, the classes are arranged either in ascending or descending order and the - - class corresponding to the cumulative frequency (cf ) just equal or greater than (N/ ) is called Q class and the value of Q is obtained by the following formula: Q L pcf N where L is the lower limit of the Q class, f is the frequency of the Q class, c is the magnitude of the Q class, pcf is the cumulative frequency of the pre Q class. Similarly third quartile value can be obtained by the same procedure with Q class by the following formula: Q = L pcf N where L is the lower limit of the third quartile class, f is the frequency of the third quartile class, c is the magnitude of the third quartile class, pcf is the cumulative frequency of the pre Q class. Similarly the same procedure is to be followed for other positional measures such as deciles and percentiles, D = L + pcf N P = L + pcf N Example .
Compute upper Quartiles, lower Quartiles, D and P , P from the following data. CI − − − − − − – Frequency CI cf − − − − − − – N= N = Table : . Q = Size of N th value =