## 1.4 Key terms

Population is the collection of all observations of interest (\(N\) represents the population size)

Sample is a subset of the population (\(n\) represents the sample size)

Parameter is a specific characteristic of a population

Statistic is a specific characteristic of a sample

Variable (random variable), usually notated by capital letters such as \(X\) and \(Y\), is a characteristic or measurement that can be determined for each member of a population.

**Example 1.6 **Determine the key terms in the following study: we want to know the average (mean) amount of money spent on school supplies, including books, of students who graduated last year at ABC college. Fill in the letter of the phrase that best describes each of the items.

- Population___ 2. Statistic___ 3. Parameter___ 4. Sample___ 5. Variable___ 6. Data___

- all students who attended the college last year
- the average amount of money spent on school supplies of all students who graduated last year
- \(365.7\), \(20.1\), \(399.4\), etc.
- a group of \(100\) students who graduated from the college last year, randomly selected
- the average amount of money spent on school supplies of students who graduated last year
- all students who graduated last year
- the average amount of money spent on school supplies of \(100\) randomly selected students who graduated last year