Chapter 1
An Introduction to Statistics

I. Rounding

A. Everything is rounded to three decimal places (thousandths)

B. If the fourth digit is 4 or less then drop all digits past three

1/3=.3333333 rounds to .333

C. If the fourth digit is 5 or greater then round up

1/7=.1428571 rounds to .143

II. Hypotheses

A. A possible explanation for the behavior being studied that is based

on previously gathered facts and theories.

B. The null hypothesis....No change in behavior

C. The research hypothesis....Behavior will change

because of the experimental manipulation

III. Variables

A. Events or qualities that can assume more than one value.

B. Independent variable....A factor that is selected and manipulated,

or controlled by the experimenter.

C. Dependent variable....A measurable behavior that is exhibited by

the participant in the research.

D. Extraneous variables....Variables that may effect the outcome of a

study but are not directly related to the study.

IV. Scales of Measurement

A. Nominal....The simplest form of measurement and is used when

the variable being measured is qualitative

B. Ordinal....The simplest quantitative scale of measurement

This scale requires that you rank the data from highest to lowest.

C. Interval....Indicates relative rank as well as equal distances

between the scores, but it does not have a meaningful zero point.

D. Ratio....This scale has all the properties of an interval scale, but in addition

it has a meaningful zero point.

V. Populations and Samples

A. Population....All members of a certain defined group

B. Sample....A small representative group selected from a population

Copyright © 2004 by Mark W. Vernoy