1. Copyright 2010, The World Bank Group. All Rights Reserved. Managing Coding Operations Section B 1

2. Copyright 2010, The World Bank Group. All Rights Reserved. Creating Batches Homogeneity –Alike items within a batch –Helps to keep samples representative Batch Size –Rule-of-thumb: ½ to 1 day of work –Very small batch  frequent QC, more paperwork –Very large batch  delayed feedback, more rework 2

3. Copyright 2010, The World Bank Group. All Rights Reserved. Returning Materials from the Field What needs to be returned from the field? How should these items be packed and sent, including control forms? Provide field staff with instructions and materials for proper returns Develop tracking system to verify completeness of returns at each level Develop receipt, unpacking and check-in procedures 3

4. Copyright 2010, The World Bank Group. All Rights Reserved. Storage Room Operations Check-in should include geographic area, number of forms, and other materials by EA (map, listing sheets) These materials are grouped by batch, and given a batch ID that corresponds to a geocode Batches are shelved and tracked through processes 4

5. Copyright 2010, The World Bank Group. All Rights Reserved. Acceptance Sampling Plan 5 The process of accepting or rejecting a lot (batch) of work by inspecting a sample selected according to a predetermined sampling plan

6. Copyright 2010, The World Bank Group. All Rights Reserved. Acceptance Sampling Risks Producer’s risk (Type I error) –Rejecting good batches Consumer’s risk (Type II error) –Accepting bad batches 6

7. Copyright 2010, The World Bank Group. All Rights Reserved. Operating Characteristic (OC) Curves OC Curves characterize acceptance sampling plans. OC Curves are graphical representations for the probability of acceptance (P a ) for every possible number of errors in a batch (p). 7

8. Copyright 2010, The World Bank Group. All Rights Reserved. Example OC Curve 8 C=6, N=200 C=12, N=400

9. Copyright 2010, The World Bank Group. All Rights Reserved. Increasing Sample Size 9 n=400, c=2 n=240, c=2 n=80, c=2

10. Copyright 2010, The World Bank Group. All Rights Reserved. Varying Acceptance Number 10 n=110, c=2 n=110, c=1 n=110, c=0

11. Copyright 2010, The World Bank Group. All Rights Reserved. Acceptance Sampling Trade-Off Sampling Size vs. Acceptance Criteria –Assuming a set quality level, we can make choices regarding inspection rates and acceptance criteria –To decrease inspection rate, we must tighten acceptance criteria –To allow more defects, we must increase sample size 11

12. Copyright 2010, The World Bank Group. All Rights Reserved. Acceptance Sampling Inspection Start with 100% inspection and appropriate acceptance number for level of quality When a batch passes, reduce inspection on that coders work to sample inspection If sample inspection fails, return to 100% inspection 12

13. Copyright 2010, The World Bank Group. All Rights Reserved. 100% Dependent Acceptance Sampling Assign a coder’s completed batch to a verifier Verifier reviews all questionnaires and writes codes on separate form when they don’t agree with coder Supervisor compares the two and decides correct code when the coder and verifier codes differ An error is attributed to the coder/verifier not chosen as correct and the batch is either passed or failed 13

14. Copyright 2010, The World Bank Group. All Rights Reserved. Sample Dependent Acceptance Sampling Verifier uses a random number table to choose the first questionnaire to review Verifier reviews all n th questionnaires afterwards until the entire batch is completed The supervisor then checks the sample, attributes errors and either passes or fails the batch 14

15. Copyright 2010, The World Bank Group. All Rights Reserved. Independent Acceptance Sampling Assign a batch to a verifier before it is coded Verifier codes questionnaires on separate form Batch is coded by coding clerk Completed batch and verifier forms are checked by supervisor who attributes errors and either passes or fails the batch 15

16. Copyright 2010, The World Bank Group. All Rights Reserved. Coding Staff Review Coding clerks –Percentage increase for verification Supervisors as a ratio to coders –Remember verification review work Assignment clerks Overall shift supervisors 16

17. Copyright 2010, The World Bank Group. All Rights Reserved. Fighting Coding Boredom Scheduled breaks Rotation of duties Working in shifts Working environment 17

18. Copyright 2010, The World Bank Group. All Rights Reserved. Staff Incentives Performance based Clear criteria for incentives Avoid across the board incentives Public recognition Non-monetary gifts 18

19. Copyright 2010, The World Bank Group. All Rights Reserved. Transitioning Production Staff Are there subsequent activities where these staff would be useful? Can choose the best staff based on operational records Saving on recruitment could be transferred to training and other activities 19

20. Copyright 2010, The World Bank Group. All Rights Reserved. Section B Quiz 1.What characteristics should batches have? 2.When do you plan for return of materials? 3.What is an acceptance sampling plan? 4.What does an operating characteristic curve describe? 5.Describe the use of multiple inspection methods in verification. 20