TESTS devices used to translate observations into numbers
1. Statistics are used for purposes of description2. We can use statistics to make inferences, which are logical deductions about events that cannot be observed directlyWHY WE NEED STATISTICS?
•Methods used to provide a concise description of a collection of quantitative informationDESCRIPTIVE STATISTICS
Methods used to make inferences from observations of a small group of people known as a sample to a larger group of individuals known as a populationINFERENTIAL STATISTICS
SCALES OF MEASUREMENT
Three important properties make scales of measurement different from one another: magnitude, equal intervals, absolute 0PROPERTIES OF SCALES
ABSOLUTE 0An absolute 0 is obtained when nothing of the property being measured exists
TYPES OF SCALES1. Nominal 2. Ordinal 3. Interval 4. Ratio
INTERVAL SCALEWhen a scale has the properties of magnitude and equal intervals but not absolute 0, we refer to it as an The most common example of an interval scale is the measurement of temperature in degrees Fahrenheit
RATIO SCALEA scale that hasall three properties
WHY IS IT IMPORTANTit defines whichmathematical operations we can apply to numerical data
FREQUENCY DISTRIBUTIONSA single test score means more if one relates it to other test scoresA distributionof scores summarizes the scores for a group of individuals.