design of the sampling frame of the 2008 French survey on disability and health INSEE Loic Midy

 Problem to solve: How can we get a high number of people with disability in the sample of our survey?  Our solution: we do a two phase survey: –Step 1: we did in 2007 a short survey called VQS on households –Step 2: we classify VQS respondants into stratums of assumed severity of disability –Step 3 : the sample of the disability survey (size ) is a stratified sampling on those stratums

This methodology will be of good quality only if all the 3 steps have themselves a good quality. This raises 3 issues tackled in this presentation  Issue 1 (linked to step 1): how should we design the short set of questions of VQS in order to detect people with disability?  Issue 2 (linked to step 2): how should we do the classification of VQS respondants into stratums of severity of disability?  Issue 3 (linked to step 3):what rules should the stratified sampling of the disability survey follow?

Issue 1: design of VQS questions Global philosophy: disability\handicap is a multi dimensionnal issue. Backed by a study of the 1999 VQS data on the people aged 16 or more: 2,4% persons declared a global limitation for 6 months or more but not a single functionnal limitations (7 questions). 13,3% persons declared a least one functionnal limitation but no global limitation for 6 months or more. 14% of the persons who have an official recognition of a disability\ handicap don’t think they have a disability\ handicap !!!

Issue 1 (2) Dimensions included in the 2007 VQS  Questions on health (mini module 1 and 2)  Question on limitation (mini module 3)  Questions on functionnal limitations  Questions on help (human, technical, and housing adaptations)  Question on self perception of handicap  Question on official recognition of handicap

Issue 1 (3) the intellectual and psychical handicap were not well detected with the 1999 VQS questions: 48% of HID respondants who declared that they often put themselves in danger answered NO to all 1999 VQS questions. 63% of HID respondants who declared that people often reproached them to be to agressive or to impulsive answered NO to all 1999 VQS questions.

Issue 1 (4) => we added 4 questions to detect those handicap. Those 4 questions where asked in another survey on adults asking an official recognition of handicap where the real impairment is available (coded by a general practitionner using the medical files)

Issue 1 (5) questionsIntellectual impairment Psychical impairment sensibi lity specifi city sensibi lity specifi city Concentration0,540,590,580,64 Memory0,590,500,620,53 initiatives0,680,610,600,65 Problem solving0,720,650,540,67 A least one positive answer 0,870,330,840,37

Issue 2 We used 2 methods to classify VQS respondant: One is based on a score The second is a mixed classification

Issue 2: score Principle:  A note is assigned to each answer. Ex: question How is your health in general –Answer very bad=>5 points –Answer bad=>3 points  Final score for a person=(sum of note)\ (maximum sum of note)*100 => partial non response taken into account  Allocation of each person to a stratum according to his score (ex: if score>80 => stratum 4). –Arbitrary threshold –OR hierachical classification on a sample of persons on variable final score

Issue 2 (2) How can we assign a weight to each answer? In 1999 we had a VQS survey and then a disability survey called HID. We detect the VQS 1999 questions explaining the best one HID variable by a logistic regression => Gives an idea of the most important VQS questions BUT not perfect nor complete because VQS 1999 and VQS 2007 are not all the same (questions added, deleted, reformulated)

Issue 2 : mixed classification The steps are:  Basic imputation on missing data : non response => imputation answer NO.  Analysis of multiples correspondancies (ACM)  Classification (mobile centers méthod: SAS: FASTCLUS) on the firsts axes of the ACM=> clusters  Hierarchical classification (SAS: CLUSTER) on the clusters

Issue 2 (2): comparisons (temporary data)

Issue 3  what rules should the stratified sampling of the disability survey follow?  We have 4 stratums of severity of handicap from 1 (no handicap at all) to 4 (important handicap).  We sample 100% of people in stratum 4. The main question is which percentage of people should we sample in stratum 1?

Issue 3 (2) We should estimation confidence interval on variable of interest to answer BUT is this case the calculus are very difficult=> study of the dispersion of the weight.

Estimation for 2008 disability survey (temporary data) Data from the 1999 disability survey Quantile Estimate of weights 100% Max % Max % % % % % % % Q % Q % Median % Median % Q % Q % 29310% 188 5% 2215% 110 1% 1031% 51 0% Min 290% Min 28