Define observational study and designed experiment. What will ...

[tfester]

Define observational study and designed experiment.
 
  What will be an ideal response?

Question 2

A census bureau collects information about the household income (total income of everyone living in one residence) of people in a certain country.
  (i) Identify the variable and population under consideration.
 
  (ii) By consulting the most recent census data, it was found that the mean household income of all residents in the country is 35,352. Decide whether this descriptive measure is a parameter or a statistic and use the correct notation to express the result.

[Kingjoffery]

Answer to Question 1

In an observational study, researchers simply observe and measure specific characteristics as in a sample survey. In a designed experiment researchers apply some treatment and controls and then proceed to observe its effects on the subjects and take measurements.

Answer to Question 2

(i) The population consists of all heads-of-household in the country. The variable of interest is the household income of each residence.
(ii) The mean of 35,352 is a parameter since it is derived from the entire population. Thus, we write  = 35,352.

[tfester]

Thanks for the timely response, appreciate it

[ryhom]

Excellent