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SURFing with Statistics New Zealand. Statistics Teachers' Day 30 November 2007. Nathaniel Pihama and Deborah Brunning Statistics New Zealand. What you will see today. SURF for Schools The Statistics New Zealand website Table Builder ..and some ideas on how to use them!.
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SURFing with Statistics New Zealand Statistics Teachers' Day30 November 2007 Nathaniel Pihama and Deborah Brunning Statistics New Zealand
What you will see today • SURF for Schools • The Statistics New Zealand website • Table Builder ..and some ideas on how to use them!
Overview: • Confidentiality – Big Picture • SURF??? • What is it? • How and why did we make a SURF? • What teachers and students can do with the SURF
What is a Unit Record File? Other names • Data set • Unit Record Data set • Microdata
Confidentiality Non release The pocket Safe Unsafe Useless Useful Raw dataset
Confidentialised Unit Record Files Confidentiality methods include: Categorical Data • Global recoding • Local recoding • Numerical Data • top/bottom coding, • capping, • rounding,
What is the SURF? • Data from 200 synthetic respondents. • Target population is those aged 15-45 in paid employment. • 7 variables
What does the SURF look like? The first 7 of 200 complete unit records
How to start SURFing? • The gender gap (Level 3 and 4) • Do more females have higher qualifications than males? • Is this different from how it was in the past? • Am I average? (Level 4) • What defines the average person? • Under pressure? (Level 5) • Are people who have never been married different from married people? • Equal Pay! (Level 6) • Are males and females paid equally? • Money for nothing (Level 7) • Investigating hours worked by employees in a company • Should I do a degree? (Level 8) • Investigation into whether getting a degree helps improve earning power http://www.stats.govt.nz/schools-corner
Task -Money for Nothing • A large company is concerned that it has too many employees who do not work a 40-hour week. • You have been hired to investigate the working patterns of the employees.
How ‘school friendly’ is SURF???? • SURF Excel spreadsheet • Records are in random order • First 30 records could be used for manual data analysis • Use Excel How???????
An example of how to take a stratified sample Add Age_10 variable Add random numbers (then paste special as values)
Sort on random numbers Use filter – copy and paste records
Box plots !!!! QUARTILE function SORT by Marital
Trend line in a scatter plot Good for quick visual check Provides equation & R-sq But no residuals Plot the data (XY scatter) (tidy plot up) Add Trendline Chart menu > Add trendline Options tab Regression and Residuals
Using Excel functions – SLOPE(), INTERCEPT(), RSQ() Copy cell ref into formula bar Regression and Residuals
Regression and Residuals - Easy to create predicted values and residuals (can copy formula and use $)
Regression and Residuals - Plot the residuals
Stats NZ Products and Services • Schools Corner • Full of resources based on the curriculum. • Information releases – Hot Off the Press • Full of highlights, commentary, technical notes and tables! • New Zealand in Profile • Quick stats of New Zealand for 2007 • Analytical reports • Contain in depth analysis, background and technical information • Table Builder • Customisable tables of released survey data
Stats NZ Products and Services • Schools Corner • Full of resources based on the curriculum. • Information releases – Hot Off the Press • Full of highlights, commentary, technical notes and tables! • New Zealand in Profile • Quick stats of New Zealand for 2007 • Analytical reports • Contain in depth analysis, background and technical information • Table Builder • Customisable tables of released survey data
Stats NZ Products and Services • Schools Corner • Full of resources based on the curriculum. • Information releases – Hot Off the Press • Full of highlights, commentary, technical notes and tables! • New Zealand in Profile • Quick stats of New Zealand for 2007 • Analytical reports • Contain in depth analysis, background and technical information • Table Builder • Customisable tables of released survey data
Stats NZ Products and Services • Schools Corner • Full of resources based on the curriculum. • Information releases – Hot Off the Press • Full of highlights, commentary, technical notes and tables! • New Zealand in Profile • Quick stats of New Zealand for 2007 • Analytical reports • Contain in depth analysis, background and technical information • Table Builder • Customisable tables of released survey data
Battle for the ‘greener suburb’: an example of using case data from Table Builder
The statistical investigation cycle:(Wild and Pfannkuch, 1999) • Problem – the statement of the research questions • Plan – planning the procedures used to carry out the study • Data – the data collection process • Analysis – the summaries and analyses of the data to answer the questions posed • Conclusion – the conclusions about what has been learned.
Battle for the ‘greener suburb’:an example of using case data • Comparing the ‘traveling to work’ habits of area units within Auckland. • Which area has the ‘greener’ workers? • Walking / Running / Cycling • Public transport • Carpooling? • Working at home?
Battle for the ‘greener suburb’:where to find the data • We want a data source that contains information about modes of travel to work by area units. • Luckily, we have the 2006 Census of Population and Dwellings on Table Builder!