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1.Defining and Collecting Data (1.5 Types of Survey Errors (Nonresponse…
1.Defining and Collecting Data
1.1 Defining Variables-operational definition
Measurement Scales
Ration scale
Nominal scale
Interval scale
Ordinal scale
Classifying Variables by Type
Categorical
Discrete
Numerical
Continuous
1.2 Collecting Data
Population and Samples
A population contains all the items or individuals of interest that you seek to study
A sample contains only a portion of a population of interest
Data Sources
Primary data source
Secondary data source
1.3 Types of Sampling Methods
Probability
sample -select items based on known probabilities
Simple random sample
-every items from a frame has the same chance of selection as every other item-subject to variation and time consuming and expensive
Sampling without replacement
Sampling with replacement
Systematic sample
k=N/n
Stratified sample
Cluster sample
Non-probability sample
-select the items or individuals without knowing their probabilities of selection
advantage-convenience, speed and low cost-informal approximation, small scale initial or pilot analyses
Convenience sample
Judgement sample
Frame
-a complete or partial listing of the items that make up the population from which the sample will be selected
Data preparation
Stacked and unstacked variables
Recoding variables
Data formatting
Data cleaning-missing values and outliers
1.5 Types of Survey Errors
Nonresponse error
sampling error
Coverage error
Measurement error
Ethical error