Presentation on theme: "Describing Data Charts and Graphs. Lecture Objectives You should be able to: 1.Define Basic Terms 2.Recognize Types of Data and Data Scales 3.Draw appropriate."— Presentation transcript:
Describing Data Charts and Graphs
Lecture Objectives You should be able to: 1.Define Basic Terms 2.Recognize Types of Data and Data Scales 3.Draw appropriate graphs based on type of data and type of analysis desired. 4.Interpret the graphs
Basic Terms 1.Data, Information, and Knowledge 2.Populations and Samples 3.Variables and Observations Types of Data: 1.Categorical and Numerical 2.Cross Sectional and Time Ordered
Data, Information, and Knowledge Data Information Processing Analysis Reports Application Meaning Relevance Knowledge
Populations and Samples Sample: Subset of collection Described by Statistics Population: Collection of all possible entities of interest Described by Parameters Statistical Inference Art and science of using samples to make conclusions about populations.
Variables and Observations Entity Height (inches) Weight (pounds) Age (years) Sex (Category) Person 1 Person 2 Person 3 * * * * Male Female Male * OBSERVATIONSOBSERVATIONS VARIABLES Measurement
Types of Data: Categorical and Numerical CategoricalNumerical
Data Scales Data are generally classified into four types: 1. Nominal – Categorical data 2. Ordinal – shows ranks, intervals may vary 3. Interval – intervals are constant, arbitrary 0 4. Ratio – Numeric data with a real 0 value. Ordinal, Interval and Ratio scales are all Numeric data.
Types of Data: Time Series and Cross-sectional Population Month(Millions) PopulationGDPGender Country(Millions)$ BillionRatio USA China India600 Nigeria100 Japan120 Canada30 Variable(s) over time Variable(s) at one point in time across multiple entities (countries in this case)
Numeric Data (Interval or Ratio): Frequency Tables A Frequency Table showing a classification of the AGE of attendees at an event. Relative ClassFrequency Percent 10 to to to to to
Frequency Histograms A graphical display of distribution of frequencies
Developing Frequency Tables and Histograms 1.Sort Raw Data in Ascending Order: 12, 13, 17, 21, 24, 24, 26, 27, 27, 30, 32, 35, 37, 38, 41, 43, 44, 46, 53, 58 2.Find Range: = 46 3.Select Number of Classes: 5 (usually between 5 and 15) 4.Compute Class Interval (width): 10 (range/classes = 46/5 then round up) 5.Determine Class Boundaries (limits): 10, 20, 30, 40, 50 6.Compute Class Midpoints: 15, 25, 35, 45, 55 7.Count Observations & Assign to Classes