1. Sampling for Detailed NDIP Inspections Emma O’Keefe StR in Dental Public Health Presented at NDIP Coordinators’ Study Day 26 th July, 2010 (Updated 2014 in relation to sampling at CPP (Community Planning Partnership Level))

2. Aims & Objectives To give a working example of how to carry out sampling at Board Level and CHP or CPP level

3. Why? Consistent Comparisons Opportunity to share experiences

4. Why sample? Resources Necessary Random and representative Sufficient size

5. Sampling protocol State maintained schools Minimum sample of 250 per area Select additional 15-20% All children in class Refresh sample each year

6. Sampling- Step 1 Board Area Worked example Lists from Local Education Dept. Exclusions 141 schools 3732 pupils 216 classes

8. Example School + Class CHP or CPP Number in Year Number in Class A1X19 A2iZ5124 A2iiZ5127 A3Y31

9. Sampling- Step 2 Divide according to school year size Divide into: Small (1-15) Medium (16-49) Large (50+)

11. Summary school information No. pupils in school yearTotal Small (1-15) Medium (16-49) Large (50+) Year Population 319239610173732 No. of schools 408417141

12. Calculate no. of pupils and schools to inspect Year SizeNo. of schools No. of children % of Board year population Sample required Small403198.526 Medium84239664.2193 Large17101727.382 Total1413732100301

13. Sampling Step 3 Random numbers 3.1 Generate random numbers (>0 to <1) Select column to input random no. Use Σ function (more functions) Select RAND Press OK

14. Sampling Step 3 Random numbers 3.2 Will give random no. in top cell Select that cell Click on little box bottom right Click and drag down column Populate random no. in all cells

15. Sampling Step 3 Random numbers 3.3 To set random number values –Highlight random numbers –Copy column –Paste Special –Select Values option –Random numbers will be held

16. Sampling Step 3 Random numbers 3.4 Each school class assigned random number Sort by random no. column

18. Calculate no. of pupils to inspect No. pupils in school yearTotal Small (1-15) Medium (16-49) Large (50+) Year Population319239610173732 Proportion of year population (%) 8.564.227.3100 No. of children required to sample 2619382301

20. Calculate no. of pupils and schools to inspect Year Size No. of schools No. of children % of Board year population Sample required No. selected schools (pupils) Small403198.5266 (28) Medium84239664.219310 (199) Large17101727.3824 (88) Total141373210030120 (315)

21. Sampling at CHP/CPP Level Why? –Local comparisons –Local planning How? –Minimum of 250 per CHP/CPP area –Weighting (carried out by ISD)

22. Sampling protocol State maintained schools Minimum sample of 250 per CHP/CPP Select additional 15-20% All children in class Refresh sample each year

23. Sampling- CHP/CPP worked example Lists from Local Education Dept. Exclusions 3 CHP/CPP areas 141 schools 3732 pupils 216 classes

25. CHP/CPP Level Sort into separate CHPs/CPPs Sort by school year size Allocate random numbers Sort by random numbers Select classes to inspect

26. CHP/CPP pupils in school year CHP /CPPSchool Year SizeTotal SmallMediumLarge X375614681066 Y13910244191582 Z1438111301084 Total319239610173732

27. No. pupils to inspect per class size per CHP/CPP to get sample 300 CHP/CPPSchool year sizeTotal SmallMediumLarge X10158132300 Y2619480300 Z4022436300

29. Completed sampling for CHPs/CPPs No. selected schools (pupils) Year SizeXYZ Small3 (11)2 (27)9 (44) Medium10 (180)11 (208)12 (245) Large7 (151)3 (84)2 (51) Total20 (342)16 (319)23 (340)

30. Weighting Results need to be weighted for average for NHS Board area CHP/CPPSample size School Yr% inspected X300106628 Y300158219 Z300108428 Total for NHS Board 900373224

31. Reference Pine CM, Pitts NB, Nugent ZJ. BASCD Guidance on Sampling for Surveys of Child Dental Health. Community Dental Health 1997; 14 (Supplement 1):10-17. Found www.bascd.org in policy section under guidance dated Friday 23 rd January 2004.www.bascd.org

32. Useful websites www.scottishdental.org www.dundee.ac.uk/dhsru www.bascd.org www.glac.ac.uk/departments/dentalsc hool

33. Appendix 1- CHP/CPPs