Table 1 The 10-phases of the HOP-Up physical activity environment questionnaire development

Phase 1 Literature Review

 ▪ Extensive review of published questionnaires that assess physical activity and/or sedentary activity supports and frequency of use in the home to identify key components of the home and near environments related to obesity risk

Phase 2 Item Bank Creation

 ▪ Identification of items pertinent to study purpose

 ▪ Adaptation, enhancement, and expansion of questionnaire items

 ▪ Organization of items by location category (i.e., inside the home, immediately outside the home [i.e., yards], and neighborhoods [i.e., playgrounds])

Phase 3 Initial Expert Review of Items

 ▪ Expert review (n = 6) of items to identify appropriateness, gaps in assessment, and suitability for use in homes with preschool children

Phase 4 Item Refinement

 ▪ Further item adaptation, expansion, and de novo development

 ▪ Revision or elimination of items that were age-inappropriate (e.g., presence of basketball hoop at the home)

Phase 5 Questionnaire Design

 ▪ Creation of questionnaire layout

 ▪ Development of scoring procedures

Phase 6 Content Validity Review

 ▪ Second expert (n = 8) review and refinement to establish content validity and confirm scoring procedure

 ▪ Refinement of items

Phase 7 Cognitive Testing

 ▪ Cognitive testing conducted with parents of preschoolers (n = 5) to ensure accurate comprehension and establish face validity

 ▪ Refinement of items

Phase 8 Field Testing to Establish Criterion Validity and Test-Retest Reliability

 ▪ Field-tested questionnaire with parents age ≥18 and <45 years and having at least one child 2- to 5-years-old

  ▪ Part 1: At home visits, parents and researchers simultaneously, but independently, completed the questionnaire (researchers served as the “gold standard” or criterion and followed specific guidelines)

  ▪ Part 2: ~2 weeks later, parents completed the questionnaire online again to establish test-retest reliability

  ▪ Refinement of the questionnaire based on field testing results.

Phase 9 Establishing Scale Unidimensionality, Internal Consistency, and Convergent Validity

 ▪ Factor analysis of the refined questionnaire with parents (N = 655) having at least one child 2- to 5-years-old completing baseline questionnaires for the HomeStyles intervention.

  ▪ Split-half cross-validation with exploratory (n = 327) and confirmatory (n = 330) halves to examine factor structure of the measure using Principal Components Analysis with varimax rotation (orthongonal) and Kaiser normalization to establish unidimensionality of the scales.

   ▪ Part 1: Iterative exploratory factor analysis conducted to identify strong factor solutions (minimum loading of 0.4) and eliminate cross-loading items (loadings on >1 scale within <0.2 of each other).

   ▪ Part 2: Verify exploratory factor solutions via confirmatory factor analysis.

 ▪ Calculate internal consistency of final scales.

 ▪ Test convergent validity of the final scales in parents and children with other physical activity measures.

Phase 10 Final Expert Review

 ▪ Expert review (n = 5) of items to confirm content validity of the final questionnaire.