A cross-sectional survey was conducted among children aged 7–8
years from five different primary schools in Baghdad City during September–October, 2011. Questionnaires were used to assess the living environment and IQ was assessed using standardized measures. Self-administered questionnaires were distributed to the participating children’s parents.
A list of all schools in the city of Baghdad was obtained from the Ministry of Education. Baghdad is divided into five educational areas, and one school was selected from each of them. Simple random sampling was used to select the five schools. The five educational areas represent people living a range of conditions, and include of both high and low socio-economic groups.
From each selected school, a complete list of student names was obtained. Stratified random sampling according to grade was then used to identify 106 children from each school. To avoid a possible influence of puberty on the measures of interest, children aged 7–8
years were selected as the study population.
G*Power version 3 [9
] was used to conduct a power analysis. For 95% power, 0.05 type 1 error (alpha) probability and a correlation coefficient of 0.2 (based on [2
]) the minimum sample size required was 266 children.
The Raven’s Colored Progressive Matrices (CPM) test was used to obtain child IQ score, with a maximum total score of 36 points. The test consists of 36 items in three sets of 12: A, AB and B. It is designed for use with young children for anthropological studies and for clinical work. It can be used with people who for any reason cannot speak the English language [10
]. Any score higher than the 75th
percentile is considered to indicate a high IQ whereas a score below the 75th
percentile is considered to indicate a low IQ.
Parents who were illiterate or had primary education (the first stage of compulsory education) were classified as having low education. Parents who had secondary school education (the final stage of compulsory education) or a university degree were classified as having high education. Family monthly income details were obtained from the parents and then categorized into low or high income depending on the median family monthly income published by the Iraqi Central Statistical Bureau [11
The living environment was defined as the place where the child’s family is living. An insecure living environment was defined as lacking a sense of security or affording no ease or reassurance, wherein the living situation is threatened. The living environment questionnaire consists of three domains: physical safety (hearing any gun shots or explosions, or seeing dead bodies), mental stress (worrying about child safety, child witnessing any type of explosion, thinking of leaving the house and relocating to a different area, thinking the living area is insecure), and public services (water quality, hours of electricity supply).
The questionnaire consists of 13 items, each with three response options: never (2), Occasionally (1) and Frequently (0). The maximum total score was 26. A score of 13 was taken as the cut-point because if the respondents were to answer ‘most of the time’ for all questions, the total score is 13. Any score less than 13 indicated a poor living environment, whereas a score above 13 indicated a good living environment.
A pilot test of the questionnaires was carried out among 31 parents. Back-to-back translation was conducted to validate the questionnaires in Arabic language. Face validity was also tested. The living environment scale had a good internal consistency, with a Cronbach’s alpha coefficient of 0.827.
The study was approved by the Research and Ethics Committee of the Universiti Kebangsaan Malaysia Medical Centre. Also approval from Iraqi ministry of education was obtained to conduct the research inside the schools.
The association between child IQ status and living environment status (good/poor) was examined by a Chi squared test (for categorical variables). A logistic regression analysis was conducted to determine the factors associated with IQ status. Odds ratios were obtained for each potential factor after adjustment for age, sex, school grade, family income and parent education level. The mental stress, physical safety and public services domains were treated as continuous variables. The reference for gender was male, for educational level was high, and for family income was high. All analyses were performed using SPSS version 16.0 [12