Teaching with Stata

Teaching with Stata Alan C. Acock & Peter Lachenbruch Oregon State University alan.acock@oregonstate.edu peter.lachenbruch@oregonstate.edu

Teaching with Stata in a SPSS College • When I started teaching with Stata • 90% of the faculty used SPSS • 10% used SAS • Stat Transfer is a powerful argument • SPSS can save a Stata file for people use to using SPSS for data management • Faculty using SPSS rely mostly on its excellent menu system • Students who know Stata can use SPSS menu 2007 WCSUG Presentation 2

Need Colleagues • College had good fortune of hiring Tony • Impeccable statistical qualifications • Long history of using Stata • Use Stata’s strengths to get colleague support • Long & Freese Limited Dependent Variables • gllamm • Complex sample capabilities • ice, mim • Many of these are user written 2007 WCSUG Presentation

Need Colleagues • College Methodology Core presentations • Students’ presentations doing things not possible with SPSS • Recruit Faculty Projects to using Stata & have Faculty presentations • Emphasize what Stata can do rather than attacking SPSS--advantages are obvious • Faculty inertia is like herding cats 2007 WCSUG Presentation

It’s Hard to Convince Menu Addicts • Most colleagues have a research team & need to coordinate their work • Need to plan data management & analysis • Need to maintain a record of all changes to data • Need to have comments • Need to organize & understand datasets • Need to replicate data modifications • Need to replicate results • Need to do “revise & resubmit” re-analysis 2007 WCSUG Presentation

Convincing Menu Addicts Appropriate use of menu system • Nobody ever needs to replicate your results • No other people working as part of a team • All your manuscripts are published without need for revisions • Learning about options w/o reading the manuals • I use them with graphs & then copy to a do-file 2007 WCSUG Presentation

Convincing Menu Addicts • Refuse to help student w/o all relevant do-files • I should be able to stick their flash drive in my PC and have their data created and analyzed • Require appropriate comments • Students never imagine how much they can forget • Need write comments so somebody else can use the program 2007 WCSUG Presentation

Command Structure--Stata’s Great Strength • I show the Stata program in class • I require the Stata program to be submitted with all labs • In presentations, I sometime[s] show SPSS or SAS code that can duplicate Stata • without stressing how bizarre it is • ”type a little, get a little” is compelling by comparison to SPSS/SAS • regress y x1 x2, beta • logit y x1 x2, or • poisson y x1 x2 • factor x1 - x12, pcf 2007 WCSUG Presentation

Working with Graphs • Many introductory statistics courses minimize graphic presentations • Many students & colleagues rely on Excel for graphs • Stata 10 has a professional quality graphs • Graphics editor in Stata 10 gives students a sense of efficacy it is hard to get with most statistics procedures • Stress knowing their audience--bar chart or histogram may be most effective for non-technical audience • Stress need to have strong statistical evidence behind the graph, even when not reported • Two-way graphs with multiple overlays--scatter, linear, quadratic 2007 WCSUG Presentation

What to do in Labs--Motivations • My undergraduates are in the social & behavioral/health sciences • All state programs in Oregon are required to justify their existence on a regular basis • Funding for new programs is part of many positions • Substantive content gets first job; ability to write/evaluate program proposals get promotions • Labs focus on statistics/graphs, data access, & analysis that facilitate evaluating programs 2007 WCSUG Presentation 10

What to do in Labs--Activities Class/group conduct a survey near start of course N of 100 is nice, 50 is critical Let class/group pick the topic Each enters some data & then use append Label variables, values, missing values Create a scale using rowmean/rowtotal Cover alpha after corr Use their survey data to write short advocacy Use their survey for several types of analysis 2007 WCSUG Presentation 11

What to do in Labs--Activities Class/group survey Require them to have some items that are not simple to code Skips Select all that apply Ranking of five items This helps them with coding, data entry, & data management tasks Lab reports should emphasize interpretation rather than just getting the right “number.” 2007 WCSUG Presentation 12

What to do in Labs--UCLA Stata Portal Give them assignments to find instruction on selected topics, for example http://www.gseis.ucla.edu/courses/ed230a2/notes/effect.html for effect size Search Stata’s FAQ for some topic we provide Do exercise based on UCLA video Students played jeopardy as review for tests Elements of research methods introduced wherever I can—This helps to make statistics seem more relevant 2007 WCSUG Presentation 13

What to do in Labs--Activities Use real data for most analyses Require some data management for many of the assignments W/O this, they quickly forget how to manage data W/O this, they don’t understand importance of data management Require a do-file for many of the assignments Regular use of display for calculations gets them used to keeping Stata open 2007 WCSUG Presentation 14

What to do in Labs--Activities Have them keep a portfolio Include all lab activities Include notes from lecture Include exercises they did that were not required Include activities for class I give them full credit if this looks fairly complete. It is a small portion of the grade They often go back to these in subsequent coursework 2007 WCSUG Presentation 15

What User Written Commands? • Introductory graduate statistics can utilize user written commands • Here are some I like them to have in first year course • fre • Those who have SPSS background love this • ice, mim, misschk • Missing values are a profound problem in social/behavioral/health sciences 2007 WCSUG Presentation 16

What User Written Commands? Here are a couple more user written commands Long & Freese commands for categorical & count outcomes corrtab Nicer display of correlations including significance I use this when searching for examples of small, medium, & large correlations for lecture use pathreg This does path analysis quite simply & insures each equation has same N. 2007 WCSUG Presentation 17

What User Written Commands? More user commands I include for data management Center Simple, but useful User written commands like this are a great way to introduce them to writing their own commands zscore revrs Handy for reversing scores on ordinal variables 2007 WCSUG Presentation 18

What User Written Commands? User written commands I use as teaching tools to help students visualize. Many students find a visual approach more accessible than a mathematical approach beamplot mpg, over(rep78) Balance mean for interval over categorical variables clt Nice demo of Central Limit Theorem chidemo df p for df = 1, 5, 30, 50 reminds them of the CLT cordemo Does r = .5 mean the relationship is strong? 2007 WCSUG Presentation 19

What User Written Commands? User written commands I use as teaching tools pwrdemo2, n(x) diff(x) alpha(x) Where diff is the effect size Helps students understand effect size concept that is widely used in psychology ftable, ttable, ztable Students often forget their textbook Simanova Unequal N’s do not matter much when variances are similar Unequal variances do not matter much when N’s are similar When both are unequal the nominal alpha is meaningless. 2007 WCSUG Presentation 20

Classroom Management We have a server that any student can access from anyplace with internet connectivity We have a cart with 25 very cheap laptops that basically work as dumb terminals to connect to server Many students bring their own laptops Biggest problem is to keep them from email/web browsing/game playing Apply cell phone policy to laptops Walk around room or have lab assistant sit at back to monitor 2007 WCSUG Presentation 21

Classroom Management Lecture focuses on statistics; lab on Stata--but some computer work during lecture Reinforces what they are being taught Keeps them awake—especially if they are doing it Students can easily produce the correct statistics using Stata, but they have difficulty interpreting the results A statistically significant result can be trivial A confidence interval may highlight that a result is trivially different from zero effect Need to assess both substantive & statistical significance Discuss pitfalls such as explaining rare events Simulations can help them understand assumptions 2007 WCSUG Presentation 22

Room for Improvement • corr does not give significance, just pwcorr or corrtab. Beginners do not understand why. • Effect size post estimation command for all appropriate tests—APA expects to see effect size reported—would open up a huge market • Add icon on menus that will copy command at the end of the do-file, if only one do-file is open • Enhance do-file editor • Add professional quality three-dimensional graphics 2007 WCSUG Presentation 23

Room for Improvement • Missing values package including complex survey, longitudinal, & multilevel data • Develop factor analysis commands • Nice to have some way that Stata could validate the most powerful user written commands • Need book who how to systematically manage data using Stata—more than just the commands—including the philosophy behind it 2007 WCSUG Presentation 24

Room for Improvement • Need menu icon in Stata to copy directly to a do-file • Experienced users often have several concurrent do-files & Stata wouldn’t know which do-file should get the command • Beginning students usually have a single do-file • Single click option would be nice, when you have only one do-file open 2007 WCSUG Presentation 25

Discussion Topics Experience gaining support for Stata Barriers Solutions to overcome barriers Ideas for Labs Favorite user written commands for beginners Instruction Data Management Analysis Suggested Stata enhancements to make it a better tool for instruction 2007 WCSUG Presentation 26

Teaching with Stata