So, You’re Going to Write an Empirical Paper Statlab Workshop October 31 st, 2003 David Nickerson

Outline of Empirical Paper Introduction Theory Data Description Analysis Conclusion

Introduction Topic Question What specific question are you seeking to answer? Literature Review Find an empirical article whose data analysis you would like to replicate.

Theory Categorize your theory Descriptive or Causal? Dynamic or Static? Write down your theory Derive testable hypotheses from theory Direct or Indirect? Necessary and/or Sufficient?

Make a List Dependent Variable(s) Variables of Interest Control / Confounding Variables Time Period Scope Keep in Mind: Type of Analysis to be Conducted

Looking for Data Can find most data you’ll need on-line –Don’t begin by entering by hand Statlab Webpage ( –StatCat –ICPSR ( –Reference Librarian (Julie Linden) Note: All of your data may not be in one place

Once You’ve Found the Dataset Download the data and documentation Determine data file type –Probably a text file (.txt,.dat,.raw) Will need to convert data file –You need to select a statistical program to learn

Converting Text Files Delimited Files (comma, tab) –Can be read directly into virtually any program –Stat/Transfer Fixed Column Files (no delimiter) –Data Definition File (SPSS or Stata) –Text-Import Wizard (SPSS) –Write your own Data Definition File

Data Practices 1)Make a back-up of all Master Data Files Burn a CD (Best Option) Pantheon Space T-Drive (Not Secure) 2)Use Syntax Files to Manipulate Data Can go back and fix mistakes Will not erase the original data Might need to add variables or cases

Syntax Files What are they? Text-files used to enter commands in bulk Why should I use them? You will make mistakes You will need to make changes You need to document your method How do I know what to write? Program’s GUI provides the underlying command Manuals

Describing Data Where did the data come from? Who collected it? When? Where? How was the data collected? Survey? Government reports? How were key variables measured?

Descriptive Statistics Key Variables Dependent Variable(s) Independent Variable(s) Important Control Variable(s) Graphs Summary Statistics on Key Variables Number, Mean, Minimum, Maximum, Standard Deviation Cross-Tabs

Output SPSS Output File Appears automatically Can delete unwanted information Export in.txt or.html Stata Log-File Log files keep all output that appears on the screen Simple text-file (see also “outreg” command and graphing)

Putting Output into a Paper Cut and Paste Graphs Cut and Paste into Word Processing document Save as.jpeg or.tif file Tables Cut and Paste Format in Word Processing document Import into Excel, format, and then place in Word

More Advanced Analysis Multivariate regression techniques help to account for confounding factors, but can be complicated. 1)Be honest about your abilities. 2)Can teach yourself one or two statistical tricks over the course of the thesis. 3)Best off including techniques that you fully understand.

Take Away Messages 1)Use Syntax Files 2)Determine Very Precisely What You Are Asking 3)Use Syntax Files 4)Don’t Get In Over Your Head 5)Use Syntax Files