Psy 231 Stats

Psy 231 Stats/Methods I

Intro to Statistics

Chapter 1 (G & W)

Parameters and Statistics

When describing data, it is necessary to distinguish whether the data come from a population or a sample.

Typically, every population parameter has a corresponding sample statistic.

- Parameter—a value that describes a population

- Statistic—a value that describes a sample

variable--characteristic or condition that changes or has different values for different individuals.

Most research begins with a general question about the relationship between two variables for a specific group of individuals.

Descriptive Statistics

- techniques used to summarize, organize, and simplify data

- can't look at it all - get a quick, good impression

Inferential Statistics

- techniques used to study samples and then make generalizations about the populations from which they were selected

Variables

discrete - separate categories. No values can exist between two neighboring categories (e.g., dice)

continuous - infinite fineness. There are an infinite number of possible values that fall between any two observed values

•For example, time can be measured to the nearest minute, second, half-second, etc.

- each score corresponds to an interval of the scale

- the boundaries that separate these intervals are called real limits

Scales of Measurement

Arbitrary zero point---zero does NOT mean a complete absence of the attribute being measured (e.g., °F)

Equal, ordered categories

The value 0 means a complete absence of the variable being measured (e.g., height in inches, weight in lbs.)

See G&W Appendix A for a math review--I'm assuming you possess these basic skills...If not, you need to develop them before taking this class.

You must know and be VERY comfortable with the order of operations!!