Stats

Nominal

Classifies data into mutually exclusive categories. There is no ranking no significance in ordering

Ordinal

classifies data into categories that can be ranked with no precise differences, however (First second third, small medium large)

Interval

Precise differences do exist but no meaningful zero

Ratio

Characteristics of all plus true zero

Random Sample

Where all members of the population have an equal chance of being selected randomly

Systematic Sample

sample obtained by every kth number and k is a counting number (every tenth person)

Stratfied Sample

Sample obtained by dividing the population into subgroups based on some characteristic relevance, and then subjects are randomly chosen from each subgroup

Cluster Sample

Dividing the population into sections, then selecting one or more clusters at random.