How Do You Determine Task Importance in a Job Description with Multiple Factors?

Hi,

Can anyone help me to find out how to measure the importance of a task or knowledge within a portfolio of multitask factors that should be included in a job description?

Enclosed here is an example.

Please help!

Thank you so much! :-D

Dear Binababu,

I really appreciated your quick response to my query. Thanks a lot for the very good source you referred me to read. However, what I am concerned about here is how they can measure the importance of each task. It should have a formulation.

Let's take a look at the detailed description below for a typical HRM position:

%importance Category Task
79% Core Administer compensation, benefits and performance management systems, and safety and recreation programs.
78% Core Identify staff vacancies and recruit, interview and select applicants.
76% Core Allocate human resources, ensuring appropriate matches between personnel.
73% Core Provide current and prospective employees with information about policies, job duties, working conditions, wages, opportunities for promotion and employee benefits.

So, how do we determine 79%, 78%, 76% ... What I really want to find out is the formulation to define these numbers.

Please help.