Paul wants to estimate the mean number of siblings for each student in his school. He records the number of siblings for each of 100 randomly selected students in the school. What is the parameter?

A parameter is defined as a numerical or another measurable factor that conforms a set that defines a given system.

In this case, the only parameter that we have is the number of siblings that each one of the 100 students has.

For example, in a table:

#student        #siblings.

     1                       3

     2                       1

     3                        4

      ...                       ...

In the left side, we have the "number of the student" that does not really matter, because the students are randomly selected, and at the right, we can see our only parameter in this study, that is the number of siblings that each student has.

the line of