Table 1 Reworded external validity items and extent of reporting by item (n = 39 studies) *

A Population: Representativeness of target population, setting & reach of intervention

1

Are data presented on variations in participation rate in improved housing interventions by a) setting b) delivery staff/organisations c) residents (for intervention among general target population not study area)

2

Is the intended target audience for adoption clearly described

3

Is the intended target setting for adoption clearly described?

4

Is there analysis of the baseline socio-demographic and ‘condition tested’ (health status) of evaluation participants versus non-participants? (relating to evaluation population only)

B Intervention: Implementation & adaptation

5

Are data presented on consistency of implementation of intervention & its different components?

6

Are data presented on the level of training of experience required to deliver the programme or quality of implementation by different types of staff?

7

Is information reported on whether/how the intervention is modified to individuals/households within the study?

8

Are data presented on mediating factors or processes (mechanisms) through which the intervention had an impact?

C Outcomes for decision making

9

Are the reported health (even if only one measure of health is comparable) outcomes comparable to wider policy/other studies?

10

Have additional outcomes of potential adverse impacts been reported? e.g. socio-economic impacts

11

Have authors demonstrated consideration of variation in reported health outcomes (key outcome of interest) by population sub-groups, or intervention setting/delivery staff?

12

Is there sensitivity analysis of dose–response/threshold level required to observe health effect (effect on key outcome of interest not proxies)?

13

Are data on costs presented? Are standard economic/accounting methods used?

D Maintenance and institutionalisation of intervention

14

Are long term effects reported? (12 months or longer since exposure to the intervention)

15

Are data reported on the sustainability (or reinvention or evolution) of programme implementation and intervention, at least 12 months after the formal evaluation?

16 a

Is the drop-out rate/attrition reported?

16 b

Are data on attrition by baseline health status of dropouts reported and are analyses conducted of the representativeness of remaining sample at time of final follow-up (or main follow-up time point- as appropriate)?