Language Describing Data by Tables and Graphics Chapter 1 (and 0) Lectures 1-2 Week1 Language Describing Data by Tables and Graphics Chapter 1 (and 0) 11/29/2018 Language

Language What is a variable? What is an Experimental Unit? Example What is an Experimental Unit? What is a measurement (or data)? What are sampling, sample, populations? 11/29/2018 Language

Why we need sampling Example1 record Body temperature for every healthy person on Earth!!! Example2 Legislative preference in Canada 11/29/2018 Language

Data Univariate data Bivariate data Multivariate data Example 11/29/2018 Language

Descriptive and Inferential Statistics Descriptive (sample) Example Inferential Statistics (Population) 11/29/2018 Language

Types of variables Qualitative ( or Categorical) Quantitative Examples 11/29/2018 Language

Two types of quantitative data Discrete: Finitely many or countable values Examples Continuous: over an interval 11/29/2018 Language

Describing Categorical data by tables and graphs Get the information: What values have been measured How often each value has occurred Get tables or graphs as a summary 11/29/2018 Language

Graphical Tools Frequency Relative frequency Percent Rules: Sum up to n, 1, 100% respectively. 11/29/2018 Language

Example1: Summarizing an Opinion Poll by a table 280 undergrad students polled, their opinion about a proposed change in dormitory regulations. Choices are 3: Support, Oppose, Neutral. Results: 152, 51, 77 respectively. 11/29/2018 Language

Example2 ( Using graphs) 400 school administrators have been surveyed to rate the quality of public education in USA. They ranked it using A,B,C, or D. Pie chart Bar chart 11/29/2018 Language

Describing Quantitative Data Example1 The amount per category of money spent by US defense dept. in 2000 That is the Variable X=“amount of money spent” is measured for several categories Draw a Pie chart for this data. 11/29/2018 Language

Quantitative (Cont’) Example2 (Time series) When data are measured over equally spaced intervals of time. line chart. Discern a pattern. 11/29/2018 Language

Quantitative(Cont’) Stem and Leaf plot Stem component Leaf component 11/29/2018 Language

Quantitative(Cont’) Frequency Histogram plot The quantitative analogue of bar chart for qualitative Example1 GPA Example 2 airline Example 3 Discrete (weekly number of litres of milk per family) 11/29/2018 Language

Graph shape Symmetric Skewed to the right or left Unusual observations (outliers) 11/29/2018 Language