PS296 Week 1 Lecture notes (Introduction and basic concepts)
What is statistics?
The measurement of variables
– The assignment of numbers to objects.
– translating information about attributes or characteristics of cases into numbers.
– A number that does not change in value in a given situation.
– Properties of objects or events that can take on different values.
Types of variables
• Categorical variables (qualitative variables)
– Variables that divide cases into different groups or categories; measurement involves
assigning arbitrary numbers to different categories.
• Quantitative variables
– Variables that involve the measurement of some attribute; measurement involves real
• Discrete variables
– Variables that take on a small set of possible values.
• Continuous variables
– Variables that involve measurement along a continuum.
Types of data
• Categorical data (frequency data, count data)
– Data representing counts or number of observations in each category.
• Measurement data (quantitative data)
– Data obtained by measuring objects or events. Samples and Populations
– Set of actual observations; subset of a population.
– Complete set of events in which you are interested.
• Statistics (sample statistics)
– Numerical values summarizing sample data.
• Parameters (population p