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Statistical Significance Testing. Why do it? When to do it? How to it?. Testing is Important. Red shading is not statistically significant. Statements you might want to make. Estimate X is bigger than Y Estimate X this year is larger than X last year
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Statistical Significance Testing Why do it? When to do it? How to it?
Testing is Important Red shading is not statistically significant
Statements you might want to make • Estimate X is bigger than Y • Estimate X this year is larger than X last year • Estimate X is smaller than Census 2000 value • State A has the highest Value
Comparing SF3 or CTPP 2000 to current ACS Let’s do a test
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 or Z > 1.645 Difference is Significant at 90% confidence How do I do a significance test?
Obtaining Standard Error from MOE is Key • Sum or Difference of Estimates • Proportions and Percents • Means and Other Ratios There are different formulas Consult Appendix 3 in the “Compass for Understanding and Using ACS Data: What General Data Users Need to Know” Report Series. JUST CLICK HERE Where…. http://www.census.gov/acs/www/Downloads/ACSGeneralHandbook.pdf
However HELP is Here PUSH BUTTON SIGNIFICANCE TESTER trbcensus.com/notes/StatisticalCalculationsMenu.xls
But what if I am using 2000 non-ACS Data? Click Graphic and review Chapter 8 where do I get my SEs?
You will need 2 things the Standard Error and Survey Design Factor Survey Design Factor X N = Size of publication area (population) Y = Estimate of characteristic
Survey Design Factor Get Survey Design Factors from the Census 2000 SF3 Technical Documentation, Chapter 8 Table C. Mode to Work 1.4 1.2 0.9 0.7 http://www.census.gov/prod/cen2000/doc/tablec-fl.pdf Insert state abbreviation for specific state
5Y = 5* 126,540 632,700 1 - (Y/N) = 126,540 / 362,563 1- 0.3490152 0.6509848 N = Size of publication area (population = 362,563) Y = Estimate of characteristic SE = 641.7772 Solve for the unadjusted Standard Error (SE)
Survey Design Factor X 126,540 / 362,563 = 35% SE = 641.777 Survey Design Factor at 35%-see slide 10 0.7 = Final Adjusted SE = 449 Adjust the SE by the Survey Design Factor
Calculate the ACS SE from the MOE Remember at 90% Significance Standard Error equals the MOE / 1.645
A B Calculate Z and test is Z < -1.645 or Z > 1.645?
Tempting is Z < -1.645 or Z > 1.645? Green is Significant This is NOT