Categorical vs. Quantitative Variables

Categorical vs. QuantitativeVariables Identifying the Difference

Variables Come in 2 Varieties • Categorical (or __________) • Quantitative (or __________) Introduction to Statistics--Variables

Categorical Variable Characteristics • Recorded usually with words • Records which of several groups an individual belongs to • Count data in each group, but you logically should not average it • Can calculate %age distributions • Includes all yes/no questions • Graphing: best illustrated with a pie chart (but could also be a bar graph) Introduction to Statistics--Variables

Quantitative Variable Characteristics • Possible responses are numerical in nature • Includes values for which it makes sense to do operations like adding, totaling and averaging • Includes answers to how much/how many questions • Always includes ‘units’ • Graphing: best illustrated with a bar chart Introduction to Statistics--Variables

2 Types of Quantitative Variables • __________ If the Q variable is a set of isolated points on the number line, we call it this. (i.e., it’s a number but it only comes in certain values) Usually a variable that can be ‘counted’. • __________ If the Q variable forms an entire interval along the number line, we call it this. (i.e., it’s a number & it can be any value) Usually a variable that can be ‘measured’. Introduction to Statistics--Variables

Diagram of Variable Types Introduction to Statistics--Variables

Length of a pen? Type of pen? Number of pens in box? Maker of pen? Flow of ink in ml/sec? Color of pen’s ink? Point size of pen? Subject of a book? Number of pages in the book? Area of each page of book? Number of letters on a page? Number of weeks on best seller list? Categorical or QuantitativeIf Categorical, one possible category? If Quantitative, Continuous or Discrete? Units? Introduction to Statistics--Variables

Style of pants? Color of pants? Number of pairs of pants you own? # of pockets on pants? Size of pants? Maker of the pants? Length of inseam on the pants? Categorical or QuantitativeIf Categorical, one possible category? If Quantitative, Continuous or Discrete? Units? Introduction to Statistics--Variables

Reviewing Variable Types • __________ (or __________) • __________ (or __________) Introduction to Statistics--Variables

Reviewing ________ Variables • Possible responses are ________ in nature • Includes values for which it makes sense to do operations like ________, ________ and ________. • Includes answers to ________/________ questions • Includes ‘________’ • Usually—best illustrated with a ________, but ___________________________________. Introduction to Statistics--Variables

2 Types of __________ Variables • __________ If the Q variable forms an entire interval _______________, we call it this. (i.e., it’s a number & it can be any value). • __________ If the Q variable is a set of isolated ___________ _________, we call it this. (i.e., it’s a number but it only comes in certain values) Introduction to Statistics--Variables

Classwork & Homework • Use the terms you’ve learned to analyze the types of variables you encounter in the samples • Answer some the ‘usual’ questions about the nature of this survey using the data and your powers of analysis. Introduction to Statistics--Variables

Answers to Fill in Blanks Introduction to Statistics--Variables

Finding Individuals & Variables in a List Individuals in Sample—Usually in 1st Column Variables—Usually in 2nd and succeeding columns Number of in Sample = 3 Who’s in Sample? Alabama, Alaska, Arizona Variable = Region = Categorical Variable = Population = Discrete Quantitative Variable = Males = Discrete Quantitative Variable = Females = Discrete Quantitative Look for Variable Names in Column Headings Introduction to Statistics--Variables

Variables Come in 2 Varieties • Categorical (or Qualitative) • Quantitative (or Numerical) Introduction to Statistics--Variables

2 Types of Quantitative Variables • Discrete If the Q variable is a set of isolated points on the number line, we call it this. (i.e., it’s a number but it only comes in certain values) • Continuous If the Q variable forms an entire interval along the number line, we call it this. (i.e., it’s a number & it can be any value). Introduction to Statistics--Variables

Length of a pen? Type of pen? Number of pens in box? Maker of pen? Flow of ink in ml/sec? Color of pen’s ink? Quantitative, Continuous Categorical Quantitative, Discrete Categorical Quantitative, Continuous Categorical Categorical or QuantitativeIf Categorical, one possible category? If Quantitative, Continuous or Discrete? Introduction to Statistics--Variables

Subject of a book? Number of pages in the book? Area of each page of book? Number of letters on a page? Number of weeks on best seller list? Categorical or QuantitativeIf Categorical, one possible category? If Quantitative, Continuous or Discrete? Categorical Quantitative, Discrete Quantitative, Continuous Quantitaitve, Discrete Quantitative, Discrete Introduction to Statistics--Variables

Style of pants? Color of pants? Number of pairs of pants you own? # of pockets on pants? Size of pants? Maker of the pants? Length of inseam on the pants? Categorical Categorical Quantitative, Discrete Quantitative, Discrete Quantitative, Discrete Categorical Quantitative, Continuous Categorical or QuantitativeIf Categorical, one possible category? If Quantitative, Continuous or Discrete? Introduction to Statistics--Variables

Reviewing Variable Types • Categorical (or Qualitative) • Quantitative (or Numerical) Introduction to Statistics--Variables

Reviewing Quantitative Variables • Possible responses are numerical in nature • Includes values for which it makes sense to do operations like adding, totaling and averaging. • Includes answers to how much/how many questions • Includes ‘units’ • Usually—best illustrated with a bar graph, but pie chart is also possible. Introduction to Statistics--Variables

Reviewing Categorical Variables • Recorded usually with words • Records which of several categories an individual belongs to • Count data in each group, but you logically should not average it • Can calculate percentage distributions • Includes all yes/no questions • Usually—best illustrated with a pie chart. Introduction to Statistics--Variables

2 Types of Quantitative Variables • Continuous If the Q variable forms an entire interval along the number line, we call it this. (i.e., it’s a number & it can be any value). 2. Discrete If the Q variable is a set of isolated points on the number line, we call it this. (i.e., it’s a number but it only comes in certain values) Introduction to Statistics--Variables

Categorical vs. Quantitative Variables