1. Population Health Assessment The Use of 2 by 2 Tables

2. Healthy UH Healthy UnHealthy HOW TO SEPARATE THE TWO SUBPOPULATIONS? Health Assessment

3. SURVEYS SURVEILLANCE ON-GOING EPIDEMIOLOGIC INTELLIGENCE GATHERING USUALLY LONG TERM SYSTEMATIC and ORGANIZED

4. Health Assessment Unhealthy HEALTHY H UH POPULATIONSAMPLE

5. SAMPLING MUST BE: 1. UNBIASED 2. REPRESENTATIVE THIS WILL BE THE ONLY WAY TO MAKE INFERENCES

6. SAMPLING NON RANDOM.....CONVENIENCE RANDOM 1. SIMPLE RANDOM 2. STRATIFIED RANDOM 3. STAGE BY STAGE RANDOM 4. SYSTEMATIC RANDOM

7. SAMPLING NON RANDOM.....CONVENIENCE RANDOM #1:SAMPLING PROCEDURE #2:SAMPLE SIZE Determination WITH THESE TWO CONSIDERATIONS...ONE CAN PROCEED TO ASSESS THE HEALTH OF A POPULATION UNDER STUDY Need to Have the Knowledge Base and Skills in:

8. Healthy UH Healthy UnHealthy HOW TO SEPARATE THE TWO SUBPOPULATIONS? Health Assessment The Use of TEST SYSTEMS

9. TEST SYSTEMS CLINICAL IMMUNO-DIAGNOSTIC PHYSIO-CHEMICAL OTHERS ONE COMMON CHARACTERISTICS OF TEST SYSTEMS ? FALLACIES AND INACCURACIES Health Assessment

10. TEST SYSTEMS FALLACIES AND INACCURACIES TEST POSITIVES TEST NEGATIVES WHAT DOES IT MEAN ? COULD MEAN ?

11. TEST SYSTEMS FALLACIES AND INACCURACIES TEST POSITIVES TEST NEGATIVES WHAT DOES IT MEAN ? COULD MEAN ? HOW TO ASSESS OR ESTIMATE INACCURACIES.....

12. TEST SYSTEMS TEST SENSITIVITY AND TEST SPECIFICITY AND OTHER MEASURES Se Sp F+ F- PREDICTIVE VALUES (+ or -) DIAGNOSABILITY

13. TEST SYSTEMS TEST SYSTEM + - TOTALS Refer to Exercise Test Negatives Test Positives

14. The 2 By 2 Table: How to Create it?? How to Create a 2 By 2 Table??? Why do we need it? Where do we Get the data to insert in these Tables??

15. TEST SYSTEMS TEST SYSTEM + - SUB-TOTALS D+D- STATE OF NATURE Note: How to Cross Classify to Create the 2 By 2 Table.

16. TEST SYSTEMS TEST SYSTEM + - SUB-TOTALS D+D- STATE OF NATURE ab cd a+b c+d a+c b+d n=a+b+c+d Note: How to Cross Classify to Create the 2 By 2 Table

17. TEST SYSTEMS TEST SYSTEM + - SUB-TOTALS D+D- STATE OF NATURE (Gold Standard) ab cd a+b c+d a+c b+d n=a+b+c+d Se= P(T+/D+)= a/(a+c)Sp= P(T-/D-)= d/(b+d)

18. TEST SYSTEMS TEST SYSTEM + - SUB-TOTALS D+D- STATE OF NATURE (Gold Standard) ab cd a+b c+d a+c b+d n=a+b+c+d Se= P(T+/D+)= a/(a+c)Sp= P(T-/D-)= d/(b+d) F+= P(T+/D-)= b/(b+d)F-=P(T-/D+)=c/(a+c)

19. TEST SYSTEMS TEST SYSTEM + - SUB-TOTALS D+D- STATE OF NATURE (Gold Standard) ab cd a+b c+d a+c b+d n=a+b+c+d Predictive value(+)=a/(a+b) Predictive value(-)=d/(c+d) True Prevalence=(a+c)/n Apparent Prevalence=(a+b)/n

20. TEST SYSTEMS TEST SYSTEM + - SUB-TOTALS D+D- STATE OF NATURE ab cd a+b c+d a+c b+d n=a+b+c+d DIAGNOSABILITY= P(D+/T+)= (P(D+)*P(T+/D+))/(P(D+)*P(T+/D+))+((P(D-)*P(T+/D-)) LINK

21. EXERCISE: CASE PROBLEM #1 TEST SYSTEMS EXERCISE Given True prevalence38%True prevalence IHA test positives250IHA test positives IHA positives260IHA positives Given True prevalence38% Infected/diseased250 IHA test positives260 IHA test negatives478 DATA GIVEN IHA test -47865% IHA test +26035% 738100%

22. EXERCISE: CASE PROBLEM #1 D+D-Marginal totals T+ aba+b T- cdc+d Marginal totals a+cb+dn True Prev(a+c)/n280 Apparent Hlthy(c+d)/n478

23. EXERCISE: CASE PROBLEM #1 TEST SYSTEMS EXERCISE Option #1 D+ D-Marginal totals T+25010260 T-30448478 Marginal totals280458738

24. EXERCISE: CASE PROBLEM #1 TEST SYSTEMS EXERCISE Option #1 D+ D-Marginal totals T+25010260 T-30448478 Marginal totals280458738 SeP(T+/D+)a/(a+c)89.29% SpP(T-/D-)d/(b+d)97.82% F+P(T+/D-)b/(b+d)2.18% F-P(T-/D+)c/(a+c)10.71%

25. EXERCISE: CASE PROBLEM #1 TEST SYSTEMS EXERCISE D+ D-Marginal totals T+25010260 T-30448478 Marginal totals280458738 SeP(T+/D+)a/(a+c)89.29% SpP(T-/D-)d/(b+d)97.82% F+P(T+/D-)b/(b+d)2.18% F-P(T-/D+)c/(a+c)10.71%

26. EXERCISE: CASE PROBLEM #1 Note How Data in the Table is Presented TEST SYSTEMS EXERCISE Option #1 D+ D- Marginal totals T+25010260 T-30448478 Marginal totals280458738 SeP(T+/D+)a/(a+c)89.29% SpP(T-/D-)d/(b+d)97.82% F+P(T+/D-)b/(b+d)2.18% F-P(T-/D+)c/(a+c)10.71% TEST SYSTEMS EXERCISE Option #2 T+ T- Marginal totals D+25030280 D-10448458 Marginal totals260478738 SeP(T+/D+)89.29% SpP(T-/D-)97.82% F+P(T+/D-)2.18% F-P(T-/D+)10.71%

27. EXERCISE: CASE PROBLEM #1 Note How Data in the Table is Presented TEST SYSTEMS EXERCISE Option #3 D- D+ Marginal totals T+10250260 T-44830478 Marginal totals458280738 SeP(T+/D+)89.29% SpP(T-/D-)97.82% F+P(T+/D-)2.18% F-P(T-/D+)10.71% TEST SYSTEMS EXERCISE Option #4 T- T+ Marginal totals D+30250280 D-44810458 Marginal totals478260738 SeP(T+/D+)89.29% SpP(T-/D-)97.82% F+P(T+/D-)2.18% F-P(T-/D+)10.71%

28. Bonus Question Discuss Diagnosability as a Decision Making Exercise

29. Good Luck Refer to Online Epidemiology Course @: http://www.onemedicine.tuskegee.edu