Presentation on theme: "1 Session 1 Module Introduction and Getting Started with Stata."— Presentation transcript:
1 Session 1 Module Introduction and Getting Started with Stata
22 Introduction Welcome Housekeeping Introductions Name, job, district, team
3 Module Overview Module objectives are to provide you with Skills in data analysis Keeping in mind the analysis objectives While learning the use of a specialised statistical software package Stata There will be a strong emphasis on conducting meaningful analyses and on the interpretation of the results.
44 Module content Data management Data entry principles and practices using Epi Info designing data capture screens, labelling and entering data, etc. Simple statistical analysis in Epi Info and using the statistics package, Instat. Report writing.
55 Duration and timetable MorningAfternoon Day 1 Getting started with Stata Continued Day 2 TablesProject work part 1 Day 3 GraphsProject work part 2 Day 4 Reviewing inference: estimation and confidence intervals Reviewing inference: Hypothesis testing Day 5 Tests of association in 2- way tables Sampling weights Day 6 Project work part 3: writing the report Putting it all in context
66 Module Learning Objectives At the end of the module, participants will : appreciate the power of Stata as a statistical package be able to undertake elementary data management and statistical analyses in Stata have updated their practical knowledge of the key statistical inference concepts of estimation and hypothesis testing be able to produce graphs and tables using Stata, have sufficient knowledge of Stata to be able to work independently to produce other analyses
77 Prerequisites Completion of Modules 1 and 2 At least a theoretical knowledge of statistical inference
88 Resources Stata software - version 10 This should be installed already It may need updating and a Stata package adding – see later slides Guide to survey data analysis using Stata Part 1 (Chapters 1 to 10) is used here Part 2 (Chapters 11 to 20) is supplied for reference Inference guide Used particularly in Sessions 7 and 8
9 Concepts more than software The emphasis is on the concepts of data analysis and statistical inference Using Stata Rather than just on Stata itself Here we largely use the menus and dialogues Though ways of using and reading commands are introduced Software is now easy to master It is the statistical concepts that benefit from a course
10 Learning objectives – sessions 1 and 2 These two sessions are about Stata Participants will be able to: Load and save data Explore data Using describe, codebook, summarize, etc Calculate new variables Using generate, recode, etc Add labels to variables and to levels of a factor Create subsets of data using drop and keep
11 Session Contents In this session we look in particular at: Windows and menus in Stata Opening Stata data files Stata dialogues Typing and editing commands Using Stata as a calculator Exiting Stata
12 The four Stata windows Review Stata Results Variables and window for typing Stata commands
13 The Stata menus and toolbar The three most important menus Data (for organising and managing the data), Graphics (for visual exploration & presentation), Statistics (for analysis). Data, Graphics, Statistics
14 Check Stata is up-to-date Use Help => Official updates If updating is needed, either: Do it automatically if you are connected to the internet Or use the files on the CD/DVD that are under Stata resources
15 The Data and Graphics Menus
16 Your turn Click on several menus and explain their usage to your neighbour You can deduce the menu from the logic of the task e.g. to draw a graph you go to the graphics menu! Which menu would you probably need to use to: save data? sort a data set? produce a bar chart? tabulate the data? Check by finding the dialogue in Stata
17 Stata guide Section 1.2 You use Stata as a calculator Go through this section together Check the buttons at the bottom of the dialogue They are the same on all dialogues
18 Using Stata as a calculator To perform calculations, use Data Other utilities Hand calculator Type 2+3 into the Expression slot Press the Submit button See answer in Results Window, and appearance of corresponding command in both the Results and Review windows.
19 Results from the dialogue You can get back to any dialogue box by typing db in front of the command name. e.g. db display
20 Creating an expression Click create and then complete the resulting expression builder dialogue box. Or type: display ln(10)
21 Stata guide Section 1.3 From this point you use a dataset that is supplied Check that you have a working directory And that it has the files for this module Copy them in, if not They are on the CD/DVD under Stata resources You could install the Stata package as well if you wish. Then use Files => Change working directory To set this directory for the future
22 Opening a Stata data file Use the menu sequence File, Open… select (highlight) the file named K_combined_short.dta and click on Open This will load the data from the Kenya socio- economic survey into Stata Look at the Variables Window. What do you observe?
23 Options within the Data menu
24 An example of a dialogue box Dialogue results from using the menu sequence Data, Describe data, Describe data contents (codebook)
25 In the codebook dialogue box… The Submit button instructs Stata to execute the command, leaving the dialogue box visible. The OK button does the same, but closes the dialogue box. Cancel closes the dialogue box without submitting the command to Stata. The R button resets the dialogue box to its empty form. ? gives help on the command associated with the dialogue box. The word codebook at the top of the dialogue shows codebook is the command that will be generated
26 Another dialogue box Dialogue results from using the menu sequence Data, Describe data, Summary statistics
27 Results from codebook and summarize
28 Your turn In Chapter 1 of the Stata guide, go through Section 1.3 Section 1.4 Section 1.5 Ask a resource person if you are unclear about any parts of the above sections.
29 Review What do each of these buttons do? Menus (and corresponding commands) used so far: display describe codebook list generate replace by/if//in What does each one do?
30 Your turn again In Chapter 1 of the Stata guide, go through Section 1.6 Section 1.7 Section 1.8 Ask a resource person if you are unclear about any parts of the above sections.
31 Review again Explain to a neighbour why: (3<4) gives the value 1 in Stata (3>4) gives the value 0 They then explain to you why the expression: 1 + (age>24) + (age>60) Recodes a column into the values 1, 2 or 3 (Hint – see Section 1.6 Fig 1.19 and 1.20 if you need help)
32 Typing and editing commands Professional use of Stata for data analysis benefits by some use of Stata commands These are typed into the Command Window To execute a command just press. To edit a previous command: Click on it in the review window, or use the Page-Up key – perhaps repeatedly. In the Results Window A dot appears in front of executed commands whether generated by a dialogue, or by typing the command.
33 Command for listing data In the command window, typing list region district household cluster will show the contents of each of the variables region, district, household and cluster. (Note: Stata is case sensitive) Pressing the GO button (see Stata menu bar) or the space bar allows you to scroll down the page To stop the display, press the red break icon button or press the letter q on your keyboard. To exit Stata, use: File Exit
34 Your turn yet again In Chapter 2 of the Stata guide, go through Sections 2.1 and 2.2 (You can go further if you have time) If you have your own data And it is not already in a Stata file, then: In Chapter 3 of the Stata guide, go through Sections 3.2.1, 3.2.2, And discuss importing with the resource persons
35 … and finally… Consider a data set from your own district or ministry that is available as an Excel file. Follow procedures similar to those in Section of the Stata Guide, to load your Excel data set into Stata. Save your data as a Stata file, giving it an appropriate name and noting the directory on your computer where it has been saved. Note: You will return to this data set in sessions that follow.