Table 4 Threats to internal validity
Indicator | Metric | Spill-over and contamination | Hawthorne and placebo effects |
|---|---|---|---|
Schooling | Enrolment, attendance, drop-out and completion | Children may attend school from neighbouring communities to have access to meals | Expectation of coming programme in control villages |
Cognitive ability | Raven’s matrices or other test | Very unlikely | Teachers’ and children’s attempts to over-perform in both project and control villages |
Attention | Digit span or other test | Very unlikely | Teachers’ and children’s attempts to over-perform in both project and control villages |
Learning achievement | Scores on language and math tests | Very unlikely | Teachers’ and children’s attempts to over-perform in both project and control villages |
Physical growth | Anthropometric measures of height and weight | Children from other villages may access school meals | Very unlikely |
PAL | Parents perceptions | Very unlikely | Very unlikely |
Diet diversity | Household consumption | Very unlikely | Very unlikely |
Micronutrient intake | Iron status, anaemia | Children from other villages may access school meals | Very unlikely |
Income | Farm profits | Unlikely, if food purchases are made in control villages | Very unlikely |
Social accountability | Parental monitoring and motivation | None at household level, possible at local Government level | Possible |