Unit One One-Variable Statistics
1.0 Statistic Terminology
Key Concepts
Population vs. Sample
Population: the entire group about which data are being collected.

Sample: part of a population selected so as to gain information about the whole population.

Data
Data: information providing the basis of a discussion form which conclusions may be drawn.

Primary vs. Secondary data
Primary data * data gathered directly by the researcher in the act of conducting research or an experiment.
• gathered by surveys or experiments

Secondary data * data gathered by someone other than the researcher / organization.
• found on the internet, books or magazines

Observational vs. Experimental data
Observational data
• data gathered by observation of the subject
• For example, the subject is recorded and the behaviours are noted on a period of time.

Experimental data
• data gathered through experimentation.

Categorical (qualitative) vs. Numerical (quantitative) data
Categorical data
• data that is grouped by specific categories
• categories may be ordered naturally (ordinal variables) or have no order (nominal variables)
• For example, for ordinal variables height can be naturally ordered using short, average, tall.
• For example, for nominal variables hair colour cannot be naturally ordered since no order occurs to their colours.

Numerical data * data that are in real number values * can be either discrete or continuous Variable Variable: a quantity that can have any of a set of values. Nominal vs. Ordinal Variable Nominal Variable
• a categorical variable that describes a name, label or category with no natural order
• e.g. there is no natural order in listing different types of school subjects: History does not have to follow Biology, they can be placed in any order Ordinal Variable
• a type of categorical variable that has a natural ordering of its possible values, but the distances between the values are undefined.
• usually have categorical scales
• e.g. when rating and the choices are Excellent, Good, Fair and Poor there is a natural ordering of these categories. Discrete vs. Continuous Variable Discrete Variable * a numeric variable that can assume a finite number of real values
• e.g. The sum on a pair of dice, shirt size (although we can have a non-integer value such as 15½ as a shirt size, they are still finite since we cannot have a size of 15¼.) Continuous Variable * a numeric variable which can assume an infinite number of real values. * e.g. Age, distance, heights, weight, temperature

Ex. What type of data am I?