1. Statistical Significance Testing Why do it? When to do it? How to it?

2. Testing is Important Testing is Important Red shading is not statistically significant

3. Estimate X is bigger than Y Estimate X is bigger than Y Estimate X this year is larger than X last year Estimate X this year is larger than X last year Estimate X is smaller than Census 2000 value Estimate X is smaller than Census 2000 value State A has the highest Value State A has the highest Value Statements you might want to make

4. Comparing SF3 or CTPP 2000 to current ACS Let’s do a test

5. 1.Get the Margin of Error (MOE) from ACS 1. Get the Margin of Error (MOE) from ACS 2. Calculate the Standard Error (SE) [SE = MOE / 1.645] 3. Solve for Z where A and B are the two estimates 4. If Z 1.645 Difference is Significant at 90% confidence How do I do a significance test?

6. Obtaining Standard Error from MOE is Key Sum or Difference of Estimates Sum or Difference of Estimates Proportions and Percents Proportions and Percents Means and Other Ratios Means and Other Ratios http://www.census.gov/acs/www/Downloads/ACSGeneralHandbook.pdf There are different formulas Where…. Consult Appendix 3 in the “Compass for Understanding and Using ACS Data: What General Data Users Need to Know” Report Series. JUST CLICK HERE JUST CLICK HERE

7. However HELP is Here trbcensus.com/notes/StatisticalCalculationsMenu.xls PUSH BUTTON SIGNIFICANCE TESTER

8. But what if I am using 2000 non-ACS Data? where do I get my SEs? Click Graphic and review Chapter 8

9. You will need 2 things the Standard Error and Survey Design Factor N = Size of publication area (population) Y = Estimate of characteristic X Survey Design Factor

10. http://www.census.gov/prod/cen2000/doc/tablec-fl.pdf Insert state abbreviation for specific state Mode to Work 1.4 1.2 0.9 0.7 Get Survey Design Factors from the Census 2000 SF3 Technical Documentation, Chapter 8 Table C. Get Survey Design Factors from the Census 2000 SF3 Technical Documentation, Chapter 8 Table C.

11. N = Size of publication area (population = 362,563 ) Y = Estimate of characteristic 5Y = 5* 126,540 632,700 1 - (Y/N) = 126,540 / 362,563 1- 0.3490152 0.6509848 SE = 641.7772 Solve for the unadjusted Standard Error (SE)

12. X Survey Design Factor SE = 641.777 126,540 / 362,563 = 35% Survey Design Factor at 35%- see slide 10 0.7 = Final Adjusted SE = 449 Adjust the SE by the Survey Design Factor

13. Populate the adjusted SEs in your worksheet for 2000

14. Calculate the ACS SE from the MOE Remember at 90% Significance Standard Error equals the MOE / 1.645 MOE / 1.645

15. AB Calculate Z and test is Z 1.645?

16. Tempting Green is Significant This is NOT is Z 1.645?

17. Try to do an exercise on your own?