In the GCM approach, overall, 45 parents agreed to participate, 23 (51%) in the outdoor kindergarten group and 22 (49%) in the conventional kindergarten group.
Of the 23 parents in the outdoor kindergarten group, four did not register for the online GCM program. Five out of the 23 parents were snowballed after the online GCM process had started, thus only attending the sorting and rating stages and the face-to- face validation meeting. Sixteen parents finished the brainstorm stage, 14 the sorting stage, 13 the rating stage and seven the face-to-face meeting.
Of the 22 parents in the conventional kindergarten group, three parents were snowballed after the online process had started, thus only attending the sorting and rating stages and the face-to-face validation meeting. Eighteen parents finished the brainstorm stage, 15 the sorting stage, 16 the rating stage and six the face-to-face meeting.
Among the 23 and the 22 parents in the outdoor and the conventional kindergarten groups, respectively, 18 responded in both groups to the demographic questions (78% and 82%, respectively, Table 1). Among those 18 parents in both groups, 13 (72.2%) were women, and the majorities had a long education (n=13 [72.2%] and n=11 [61.1%], respectively). In total, 14 (77.8%) of the children from the outdoor kindergarten and 17 (94.4%) from the conventional kindergarten had siblings.
A total of 97 and 132 statements were generated by the parents in the outdoor kindergarten group and the conventional kindergarten group, respectively. After removing redundant statements and minor linguistic revisions, 84 and 87 unique statements remained for the sorting and rating stages, respectively.
The multidimensional scaling analysis revealed low stress values of 0.19 and 0.21, respectively indicating that the maps were readily interpretable, and we therefore proceeded with generating the maps. After carefully reviewing the various cluster rating maps, we identified the 8-cluster solution as the optimal solution for the outdoor kindergarten and the 9-cluster solution as the optimal solution for the conventional kindergarten (Supplementary figures 1 and 2).
At the face-to-face validation meeting, discussions led to a consensus about the location of the statements, the number of concepts and the labels for each concept. In the revised maps the outdoor kindergarten and the conventional kindergarten groups generated 6 and 8 concepts, respectively. Each concept contained between six and 27 statements related to the outdoor kindergarten and 6 and 19 statements related to the conventional kindergarten (Supplementary tables 1 and 2).
The six concepts generated by the outdoor kindergarten group; ‘physical setting with a focus on outdoor life and freedom of movement’, ‘learning/freedom and pedagogical ideology’, ‘personnel’, ‘everyday life’, ‘experiences’, and ‘structure and organization’, are summarised in Table 2. The parents in the outdoor kindergarten group ranked the concept “Physical setting with a focus on outdoor life and freedom of movement” with a mean score of 3.9 as containing the most important statements. Whereas the concept with less important statements was “Experiences” with a mean score of 2.8 (Table 2).
The parents ranked “Kindergarten teachers and their pedagogic approach to children”, “Playing, smiling, and attentive adults”, "Present kindergarten teachers" and “Kindergarten teachers with a focus on well-being”, as being the most important statements (Table 3). In contrast, statements such as, “Leader with long seniority”, “Wanted a small kindergarten in relation to the number of children", “Divided zones for play activities", and “I attended an outdoor kindergarten myself as a child.” are ranked as being of minor or no importance (Table 3).
The eight concepts generated by the conventional kindergarten group; ‘Physical framework’, ‘Structure / pedagogical values / food policy’, ‘Staff and workplace’, ‘Atmosphere’, ‘Reputation’, ‘Logistics’, ‘Shifts’ and ‘Staff-to-child ratio’, are summarised in Table 4. The parents in the conventional kindergarten group ranked the concept “Atmosphere” with a mean score of 3.8 as the most important concept. Whereas the concept with less important statements was “Staff-to-child ratios” with a mean score of 2.8 (Table 4).
The parents ranked the statements “Present and committed staff”, “The general atmosphere of the institution is important”, "That the institution was located close to where we live”, “That the kindergarten teachers seemed happy and spoke warmly about the kindergarten, the personnel and the management”, as being the most important statements (Table 5). In contrast, statements such as, “Small cozy institution with few groups of children”, “We looked at the parental satisfaction survey", “That the kindergarten was in close proximity to the city oasis, playgrounds, parks, etc.", and “That the kindergarten had an outdoor kitchen so they could cook for the kids on the playground” were ranked as being of minor or no importance (Table 5).
3.2 The register-based study
In the register-based study, 2434 children had attended outdoor kindergartens and 2643 children had attended conventional kindergartens. As shown in Table 3 parents characteristics differed for the majority of the investigated socio-demographic characteristics; both maternal and paternal SES were higher among children attending outdoor kindergartens (p<0.0001) and more parents with non-Western origin chose outdoor kindergartens (p<0.0001). Also, most early child characteristics differed according to type of kindergarten, with fever children born preterm, and fewer delivered by caesarean section among children from outdoor kindergartens (5.1% vs. 7.1%, p=0.004 and 18.7% vs. 21.1%, p=0.04, respectively). Also, fewer girls than boys attended outdoor kindergartens (43.5% girls vs. 48.6% p=0.0003, Table 3), but we found no statistical significant differences related to kindergarten type in none-specified hospital admissions (p=0.08), or emergency department admissions (p=0.76), however, the latter only included children starting kindergarten prior to 2014 (n=142).