Iodine level for Children's Intelligence - forest plot outlook of analysis for groups, and subgroups

Case-control studies targeting children aged 6 to 19 years, enrolled 21,284 participants.
By applying random-effect model, RevMan 5.3., was used for the analysis with standardized mean differences at 95% confidence interval.
Forest plots of intelligence assessment firstly for children 6 9 years, 9 - 11 years, 11 - 19 years, undetermined age-cohort,
and secondly for location of rural settings’, urban settings’, and varying settings’ groupings indicative of significance with exposure to iodine status, based on factors that influence heterogeneity.