Psychological Statistics: The basics

Statistics

A branch of science, deals with the collection, presentation, analysis and interpretation of data

Desrciptive

Describing and analyzing a set of data

Inferential

A subset of data leading to predictions or inferences

Population

Is a collection of all the elements under consideration in any statistical study

Sample

Is a part of the population from which information is collected

Parameter

The numerical characteristic of the population

Statistic

A numerical characteristic of the sample, useful in research.

Qualitative

Have labels or names assigned to their respective categories, expressed in words

Quantitative

Any attribute that we measure numbers, expressed in numbers

Variable

Any characteristic or attribute of persons

Level of measurements

Nominal, Ordinal, Interval, Ratio

Categorical Variable

Nominal: Categorized without order, Ordinal: Has meaningful order

Discrete V

Countable (Number of students, cars, wins)

Continous V

Measurable, infinite possible values (Height, weight, time)

Frequency Distribution

A table/ graph showing how often each value/ category occurs

Mean

Arithmetic Average

Median

Middle value when ordered

Mode

Most frequent value

Grouped mean

Mean calculated from group frequency tables