1 Question on vision Results of the cognitive test Jeremiah Banda and Maria Martinho United Nations Statistics Division

2 Analysis of cognitive data The cognitive test included: The WG question Do you have difficulty seeing even if wearing glasses? Other questions on vision and seeing difficulties Without/With your glasses, how often do you have difficulty seeing well? … Without/With your glasses, do you have difficulty seeing and recognizing a person from 7 meters (20 feet) away? A question on the use of glasses Do you wear glasses all of the time, only for certain activities or none of the time?

3 Analysis of cognitive data (cont.) Response patterns Aim: compare replies to WG question with those to other questions Interpretation of results Purposive sample: % of cases in each pattern is not and estimate of the % in the general population. Replies to open question can suggest explanations for inconsistencies between the WG question and the other questions International comparability: do respondents in different countries interpret the question in a similar way? Wears glasses? Reported seeing difficulties? WG questionOther questions Yes/No

4 Response patterns PatternWG questionOther questionsWears glasses A No B Yes C No DYes E No Yes F No G Yes H No Yes No

5 Response patterns WG question and near/far vision questions Do you have difficulty Near vision: seeing the print in a map, newspaper or book? Far vision: seeing/recognizing a person you know from 7 meters away? ABCDEFGHTotal Gambia Philippines Paraguay … Total Inconsistency between the WG and near/far vision questions

6 Response patterns WG question, near/far vision and diff/effort questions Without/ With your glasses, Diff: how often do you have difficulty seeing well? Effort: seeing/recognizing a person you know from 7 meters away? Inconsistency between the WG and near/far vision questions ABCDEFGHTotal

7 Response patterns WG question, near/far vision and diff/effort questions ABCDEFGHTotal Near/far vision Near/far vision and diff/effort More consistent replies when the diff/effort questions are taking into account

8 Some thoughts on the glasses clause The difficulties and location of the glasses clause only explains a part of the discrepancies between the WG question and the near/far vision question then inconsistencies between diff/effort questions and WG questions should be equally high. They are not! Near/far vision & diff/effort questions WG question At the beginning Difficult to understand At the end Easier to understand If the difficulties and location of the glasses clause were the only reason for inconsistencies between near/far vision and WG questions,

9 Response patterns in detail WG question, near/far vision and diff/effort questions Replies to WG Question Highest reply among other vision questions N= = No difficulty/Never

10 Inconsistent respondents: Replies to the open question WG question, near/far vision and diff/effort questions Pattern E - wears glasses, yes to WG question Glasses clause misunderstood in WG question: 33 respondents (e.g. “ because I wear glasses ”, “ I am short-sighted ”) Near/far vision questions not able to capture respondent’s seeing problems: 11 respondents (e.g. cataracts, problem with one eye only) No clear explanation: 26 respondents Pattern F - no glasses, yes to WG question 2 respondents (both from Vietnam) reported some difficulty in the WG question: because they can see well!!!

11 Inconsistent respondents: Replies to the open question WG question, near/far vision and diff/effort questions Pattern G - wears glasses, no to WG question 15 respondents understood the glasses clause and reported no difficulty to WG question (e.g. “ I see well with glasses ”). Why do they report difficulties to the near/far vision?) No clear explanation: 4 respondents Pattern H - no glasses, no to WG question 11 respondents claim to see well (why do they report difficulties to the near/far question?) 1 does not report difficulties to WG question because he is not blind 2 wear glasses!!! (we can not use near/far question) No clear explanation: 12 respondents

12 Comparability of the WG question across countries Interpretations found in several countries: Glasses clause missed in the WG question: Kenya, Egypt, Vietnam, Argentina, Paraguay, Brazil, Mexico Glasses clause understood in the WG question: Argentina, Paraguay, Brazil and Mexico Inconsistency between WG and near/far questions for persons with problem in one eye only, cataracts, irregular blurred vision: Paraguay, Argentina, Brazil, Philippines All replies consistent: all countries

13 Comparability of the WG question across countries Interpretations found in several countries (cont.): Respondents claim to see well with glasses but report difficulties in the near/far question: Argentina, India, Paraguay, Brazil and Mexico Respondents do not wear glasses, claim to see well but report difficulties in the near/far question: Uganda, Kenya, Argentina, India, Philippines, Paraguay, Brazil and Mexico Country-specific interpretations: Report some difficulty in seeing because they see well (Vietnam)

14 Conclusions and issues to discuss ‘Even if wearing glasses’: in or out? Sometimes respondents (or interviewers?) miss it WG question interpreted in a comparable way across countries? Most response patterns and interpretations were found in several countries Inconsistencies between WG questions and near/far vision were often due to: The glasses clause can be missed in any of those questions Some disabilities not captured by the near/far vision question (such as blind of one eye)

15 Conclusions and issues to discuss Other explanations suggested for inconsistencies: A respondent that needs glasses may reply to the WG question in a hypothetical way ( If I had glasses, I would see well ) Some persons anticipate financial assistance by reporting a difficulty Ageing respondents may believe their vision is weakening Blind people do not report difficulties in near/far vision questions Illiterate people report difficulties in near vision question Only field tests can tell us if the % of people falling in the inconsistent patterns is large enough to be worrying

16 Further analyses Analyse the effect of interview difficulties Study patterns of other questions on vision issues Study open questions in relation with other questions Repeat analysis for proxy data Investigate association with socio-economic variables