**3. Methods**

Five studies from a Norwegian/Swedish research team was chosen to compare inter-organisational exercises arranged by ONSOs and OFFSOs. One of the studies provided data from three ONSO exercises. Four studies contained data from six OFSO exercises, four of the OFSO exercises were pooled into two datasets. The questionnaire used to collect data during all included exercises was the collaboration, learning and utility instrument (CLU) measuring collaboration, perceived learning and utility from 1 (strongly disagree) to 5 (strongly agree) on a Likert scale [1–5] (see the Supplementary Materials). The CLU scale has been applied in similar studies of crisis exercises [1,4,47,48]. Primarily, it was developed by a team of academic instrument-developers together with emergency practitioners from response organisations. The development was made in di fferent steps based on Stein's [21] learning theories, which have their out spring from Klabber's [49] perspectives on how institutions learn, Meyer and Rowan's 1977 decoupling theory [50], Berlin and Carlström's theories on sequential, parallel and synchronous collaboration [51]. The collaboration dimension encompassed questions about the collaborative characteristics of an exercise. The learning dimension elaborated lessons learnt from collaboration during the exercises. The utility dimension determined if the exercise was perceived to be useful during real emergencies. In addition, questions were elaborated about experience and a ffiliation.

The CLU surveys were all distributed and collected from emergency personnel in connection with inter-organisational exercises at the included ONSOs exercises. Regarding the OFFSOs exercises, the survey was e-mailed to the participants from an e-mail list. The homogeneity of the 17 items showed a Cronbach's α of between 0.68 and 0.88. Statistical significance was established at *p* = 0.05, and all tests were two-tailed [52]. The analysis stems primarily from descriptive data and regressions (bivariate and multiple). Data were imported and analysed in Statistical Packages for the Social Sciences (SPSS) version 24.0.

#### *3.1. The Context of the Survey*

The studied inter-organisational exercises were full-scale field exercises. All the organisations that normally participated in the scenario, e.g., coast guard, sea rescue, police department, fire department and ambulance services, were engaged in each exercise. Moreover, the exercises aimed to improve inter-organisational collaboration, crossing organisational boundaries during accidents and disasters. The exercises took place in different parts of Norway and Sweden (Table 1).


