An educational researcher wants to evaluate the effectiveness of a new method for teaching reading to deaf students. Achievement at the end of a period of teaching is measured by a student's score on a reading test. (Assume reading scores are integers.)
(a) What is the variable to be measured?
I number of teachers
II days in a teaching period
III number of students
IV teaching method
V reading score
What type of variable is it?
I discrete
II continuous
(b) What is the experimental unit?
I reading score
II teaching period
III student
IV teaching method
V teacher
(c) Identify the population of interest to the experimenter.
I the total number of days in the school year
II all students
III the reading scores of al students who could possibly be taught using this method 21 17

As the educational researcher is measuring the reading score to assess the effect of teaching method so, the variable to be measured is reading score.

The reading score is a quantitative variable because it can be represented meaningfully in a numerical form. Also, the reading scores are countable, so reading score is a discrete variable.

b)

The reading score of students are measured to asses the effectiveness of new teaching method so, the experimental units are students.

c)

The population of interest would be the reading scores for all students as the reading scores of students is measured by researcher. Thus, the population of interest is the reading scores of all students who could possibly be taught using this method.