Thursday, March 31, 2011

LO – Topic 5 – Coding and Cleaning Data


-          Understand purpose of coding

-          Be familiar with standard code frames, such as those developed by ABS

-          Be able to develop code frames for open response questions

-          Be able to prepare variables for analysis

-          Know how to change. collapse and reorder categories of variables

-          Know how to create new variables from existing ones

-          know how to deal with missing data

 


-          Reasons why open ended questions used: range of possible response large / response options unknown / general feelings / reasons for

-          Codes – pre existing versus developed from responses

-          Coding missing data / reasons for missing data

-          Sources of coding error

-          checking for error – valid range / filter checks / logical checks

-          changing categories

o   reduce number of categories

§  substantive – categories have something in common (eg industry based categories)

§  distributional

o   rearrange à more logical order – rearrange industries by level of unionization

o   reverse coding

-          Create new variables

o   develop scales

o   conditional transformations

o   arithmetic transformations

-          standardizing variables

o   relativity

o   units of measure not comparable

o   different distributions

-          Missing data

o   check for bias – split group in two

o   dealing with

§  delete

·         listwise

·         casewise

·         variable

§  statistical imputation

·         sample mean

·         group mean

·         random assignment

·         regression analysis

 

-           

 

 

No comments: