# Validation of the Ecological MOmentary Well-being Instrument (EMOWI) in Canadian adolescents

Marie Buzzi, Karen Patte, Yan Kestens, Grégory Moullec, Laetitia Minary, Jennifer O'loughlin, Scott Leatherdale, Nelly Agrinier, Jonathan Epstein

► To cite this version:

Marie Buzzi, Karen Patte, Yan Kestens, Grégory Moullec, Laetitia Minary, et al. Validation of the Ecological MOmentary Well-being Instrument (EMOWI) in Canadian adolescents. Quality of Life Research, 2025, 34 (9), pp.2605-2616. 10.1007/s11136-025-04001-1. hal-05492882

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1 Validation of the Ecological Momentary Well-being Instrument (EMOWI) in Canadian

2 adolescents

3

4 Authors

5 Marie Buzzi¹,², MD, MPH, Karen A. Patte³, PhD, Yan Kestens⁴,⁵, PhD, Grégory Moullec⁴,⁵, PhD,

6 Laetitia Minary¹, PhD, Jennifer O'Loughlin⁴,⁵, PhD, Scott T. Leatherdale⁶, PhD, Nelly

7 Agrinier¹,², MD, PhD, Jonathan Epstein¹,², MD, PhD

8

9 Affiliations

10 ¹ Université de Lorraine, Inserm, INSPIIRE, F-54000, Nancy, France

11 ² CHRU-Nancy, INSERM, Université de Lorraine, CIC, Epidémiologie Clinique, Nancy, France

12 ³ Department of Health Sciences, Brock University, St. Catharines, ON, Canada

13 ⁴ Centre de Recherche en Santé Publique (CReSP), Montréal, QC, Canada

14 ⁵ École de Santé Publique de l'Université de Montréal (ESPUM), Montréal, QC, Canada

15 ⁶ School of Public Health Sciences, University of Waterloo, Waterloo, ON, Canada

16

17 Corresponding author

18 Name: Marie Buzzi

19 Email address: m.buzzi@chru-nancy.fr

20 Address: Ecole de santé publique, Université de Lorraine, 9 allée du Morvan, 54500

21 Vandœuvre-lès-Nancy, France

22 Phone: +33 (0) 3 83 85 93 00

23

24 Word count: 3,842
25 **Abstract**

26 *Purpose*. There is growing interest in ecological momentary interventions to promote and
27 improve mental health in youth. However, the lack of validated measurement tools for
28 ecological momentary assessment may hinder implementation and evaluation of such
29 interventions. This study aimed to provide an initial validation of the English version of the
30 Ecological Momentary Well-being Instrument (EMOWI), which was designed for momentary
31 measurement of adolescent well-being.

32 *Methods*. Both Classical Test Theory and Item Response Theory were used to assess
33 dimensionality, reliability, and validity of the scale, as part of a cross-sectional approach, in a
34 sample of 2,504 Canadian English-speaking adolescents from the COMPASS study.
35 Examination of differential item functioning (DIF) was conducted on both gender and
36 nationality, by combining the current sample with the sample of French adolescents used in
37 the French version validation study.

38 *Results*. Confirmatory factor analysis supported a single factor hypothesis. Internal
39 consistency was high and item fit statistics were satisfactory. Correlations with existing
40 scales were consistent with pre-set hypotheses. We observed a significant overlap between
41 respondents' abilities and item difficulties, suggesting the EMOWI items adequately measure
42 people's level of well-being. DIF was statistically significant, yet negligible in effect size, for
43 several items, thus allowing the use of score comparisons across genders and countries.

44 *Conclusion*. The EMOWI seems to be a promising candidate to measure momentary well-
45 being in English-speaking adolescents. Subject to further psychometric validation in a
46 momentary context, its use could inform the design and evaluation of ecological momentary
47 interventions in the field of youth mental health in international studies.
48 **Keywords**

49 Mental Health; Ecological Momentary Assessment; Ecological Momentary Intervention;

50 Adolescence; Well-being
## 51 Introduction

The COVID-19 pandemic has underscored a critical need to promote and protect mental health in vulnerable populations [1,2]. In particular, there is growing evidence of the global burden of child and adolescent mental health across countries [3,4]. According to a 2021 UNICEF report, more than 13% of adolescents worldwide live with a mental disorder, with depression and anxiety accounting for the largest portion [5]. However, despite growing awareness of this issue, there are still major shortcomings in terms of access to mental health care [6]. In this context, the interest in "Ecological Momentary Interventions" (EMIs) has risen steeply [7–10]. EMIs, defined by Heron and Smyth as "treatments that are provided to people during their everyday lives (i.e. in real time) and in natural settings (i.e. real world)" using mobile technologies [11], represent a promising opportunity to administer individualized and more accessible mental health care to those who need it most [12,13]. In particular, children and adolescents, whose lives may be viewed as "a collection of moments" [14], could benefit from this type of intervention, as they take into account the many momentary interactions that young people have with their social and physical environment, which may in turn influence their mental health.

Development and evaluation of EMIs require measurement tools capable of capturing rapid variations in subjects' behaviors and experiences, to determine in which situations, and to what extent, these interventions are effective. Such measurements can be carried out using Ecological Momentary Assessment (EMA), a method involving the repeated collection of subjects' immediate or recent states and experiences in their natural environment. This approach enables researchers to capture variations over time or in response to contextual
factors [15], and to overcome some of the limitations of conventional evaluation methods by improving ecological validity and reducing recall bias.

In this context, we recently developed the Ecological Momentary Well-being Instrument (EMOWI) [16]. The EMOWI consists of eight pictorial items covering affective (happiness, stress, energy), cognitive (self-esteem, autonomy), as well as social aspects (loneliness, feeling of being valued, safety) of well-being. A first evaluation of the psychometric properties of the EMOWI French version in a sample of 387 French adolescents has shown promising results in terms of validity and reliability. As a short pictorial scale designed for use on numeric platforms such as smartphones, the EMOWI is well-suited to data collection in ecological momentary assessment and/or intervention studies in youth [17,18]. Given the known association between well-being and health and its lability, especially in adolescents [19-21], the wider use of the EMOWI could increase understanding of the intricate and dynamic relationships between social and environmental factors, momentary well-being, and occurrence of health outcomes, such as substance use [20] or mood disorders [22]. In turn the data generated could help build tailored interventions, targeting contexts or individuals, to promote mental health in real-time.

The objective of this study was to provide an initial validation of the EMOWI by reporting the development and psychometric properties of the English version of the scale, in a cross-sectional study of Canadian adolescents participating in the COMPASS cohort, using both classical test (CTT) and item response theories (IRT).

## Methods

*Cross-cultural co-development of the EMOWI English and French versions*
The English and French versions of the EMOWI were developed simultaneously. A thorough literature review, combined with interviews with adolescents and bilingual psychiatry or psychology professionals were conducted to identify the various dimensions of well-being and formulate the scale items accordingly [16]. The dimensions were selected and the items formulated in such a way as to be suitable for momentary measurement, and the total number of items was kept short, to reduce the burden of repeated assessment on participants. Overall, eight items were developed to cover six dimensions of interest (emotions, feeling of safety, positive relationships, vitality, self-esteem, and autonomy). Two French-to-English expert translators specialized in scientific communication were asked to translate the items of the scale which were initially developed in French. Both were native English speakers but came from different geographic regions (the United States and the United Kingdom, respectively), ensuring better coverage of potential cultural biases [23]. The two translators conducted the translation independently, before the resultant two versions were merged during a reconciliation process, as recommended by Epstein et al. [23]. An expert committee comprising the two translators, one bilingual epidemiologist from Canada, and three French epidemiologists fluent in English, discussed discrepancies between versions until consensus was achieved, and then consolidated the definitive English version of the scale [23]. No adaptation of the scale was deemed necessary by the French-Canadian expert committee to improve cultural relevance, apart from direct translation. Items and their anchoring icons, which were designed by professional graphic designers to represent each concept of interest, were submitted to one English-speaking Canadian epidemiologist and two bilingual Canadian adolescents during cognitive debriefing interviews, to ensure their relevance, representativeness, and understanding in a North American context [16].

119
120 Validation of the EMOWI English version

121 For the present study, we opted for a cross-sectional design in order to ensure that the basic
122 psychometric properties of the EMOWI English version (content and convergent validity,
123 internal consistency, and dimensionality) were satisfactory, before conducting an intensive
124 longitudinal collection that may represent a burden for participants.

125 *Sampling and questionnaire administration*

126 The psychometric properties of the EMOWI were evaluated within an English-speaking
127 subsample of Canadian adolescents that participated in the Cannabis, Obesity, Mental
128 health, Physical activity, Alcohol, Smoking, and Sedentary behaviour (COMPASS) study.
129 COMPASS is an ongoing prospective study designed to collect data annually from a rolling
130 cohort of students in Grades 9 through 12 (Secondary I-V in Quebec) and the secondary
131 schools they attend [24]. Student-level data are collected each school year via an online self-
132 reported questionnaire from full school samples of students during class time.

133 For the present work, the EMOWI was included in the online student survey in a subset of six
134 secondary schools in Ontario, Canada, that participated during the 2021-22 school year.
135 COMPASS uses a convenience sample of schools based on an active information passive-
136 consent protocol, which is important for reducing school burden and collecting robust youth
137 data by improving response rates and reducing selection bias due to loss-to-follow-up
138 [25,26]. All students not withdrawn from the study by a parent/guardian were eligible to
139 participate and could withdraw at any time. All eligible students were emailed a link by their
140 school to complete the survey online, followed by a reminder email one week later. All
141 schools designated class time for students to complete the survey. Students that were
142 absent on the day of data collection were able to complete the survey on their own time. All
143 participating students provided assent. Surveys were available for 14-18 days, with slight variations across schools in timing; they opened between April 7, 2022 and May 24, 2022, and closed between April 25, 2022 and June 7, 2022.

146 *Measures*

147 The Ecological Momentary Well-Being Instrument comprises eight items, each measuring a distinct dimension of mental well-being [16] (Figure 1). Each item includes a heading describing the dimension of interest, and a slider presented on a continuous line between two pictorial anchors. Respondents were asked to move the slider to the position that best described their experience at the moment they were answering. The slider could be positioned at one of 11 hidden steps, interpreted as a discrete score ranging from 0 to 10.

153 The overall score, which ranged from 0 to 80, was obtained by totaling the scores for all items, with reverse scoring for stress and loneliness. Higher total score indicated higher levels of well-being. The EMOWI has demonstrated validity in a sample of 387 French adolescents from the EXIST project (Exploring the mechanisms of social Inequalities in Smoking in the adolescent population during COVID-19 sanitary crisis) [16].

158 In COMPASS, all eight items of the EMOWI were presented on the same webpage.

159 Participants could choose not to answer to one or several items, and the scores for these items were considered missing.

161 **Fig. 1** English version of the EMOWI
<figure><img src="image_2.png" /></figure>

162

163 Three other scales were used in the construct validity assessment: the 10-item Center for
164 Epidemiologic Studies Depression Scale Revised (CESD-R) [27], the 7-item Generalized
165 Anxiety Disorder scale (GAD-7) [28], and Diener's 8-item Flourishing Scale (FS) [36]. All three
166 scales have demonstrated validity in adolescent populations [28-35], including in the
167 COMPASS sample [36,37]. Of note, the original 7-point Likert scale of Diener's FS was
168 simplified to a 5-point Likert scale, by omitting the "slightly agree" and "slightly disagree"
169 options, to be suitable for large school-based surveys.

170 **Socio-demographic variables.** Collected personal variables included sex assigned at birth
171 (male, female, I prefer not to say), gender identity (girl/woman, boy/man, non-binary
172 person, Two-Spirit, I describe my gender differently, I prefer not to say), age (from 12 years
173 or younger to 19 years or older), grade level (9, 10, 11, 12), and ethnicity (White, Black, East
174 Asian, Indigenous [First Nations, Métis, Inuk/Inuit], Latino, Middle Eastern, South Asian,
175 Southeast Asian, I prefer not to say, I do not know). If adolescents selected more than one
176 response for ethnicity, they were classified as "Multiethnic". Consistent with previous
177 COMPASS studies, socioeconomic status (SES) of adolescents was assessed using a score
derived from four items: (i) whether they sometimes go to bed hungry because there is not
178 enough money to buy food (yes = 0, no = 1); (ii) perceived familial financial comfort relative
to an average student in their class (more comfortable = 2, as comfortable = 1, less
180 comfortable = 0); (iii) whether they have their own bedroom (yes = 1, no = 0); and, (iv)
whether they were worried about their family paying bills due to COVID-19 (true/mostly true
182 = 0, neutral or don't know/false/mostly false = 1). Individuals scoring a 0 were reclassified as
183 a 1 due to low frequency (n = 3), resulting in a 5 to 1 scale where 5 represents higher SES and
184 1 represents lower SES [38].
185

186 Statistical analysis

187 Participants' characteristics were described using counts and percentages for categorical
188 variables and means and standard deviations for continuous variables. Patterns of missing
data were assessed using R package 'naniar' [39]. To obtain a broader understanding of the
189 psychometric properties of the EMOWI, and gather information both at the scale and at the
190 item levels, we used a combination of CTT and IRT methods.
191

192 **Content validity (CTT and IRT).** To identify any floor (or ceiling) effect, defined as a clustering
193 of more than 15% of participants at the lowest (or highest) score [40], we examined the
distributions of the responses for all items and for the global score in the subsample of
195 complete respondents, as well as the distributions of person- and item-measures using a
196 Wright map.
197 **Structural validity (CTT).** As with the French version, we hypothesized that the English
198 version of the EMOWI would have a unidimensional structure, with well-being as the higher
199 factor. To test this hypothesis, we performed a confirmatory factor analysis (CFA) with
200 desired values for the comparative fit index (CFI) and the Tucker-Lewis index (TLI) > 0.9. The
201 Root Mean Square Error of Approximation (RMSEA) and item loadings were assessed, with
202 desired values < 0.08 and > 0.3, respectively [41]. Missing values were handled using the Full
203 Information Maximum Likelihood (FIML) estimator from R package 'lavaan' [42].

204 **IRT modeling.** We built a rating scale model using the Method of Successive
205 Dichotomizations (MSD) as defined by Bradley and Massof [43]. This method applies the
206 dichotomous Rasch model as many times as there are thresholds and estimate parameters
207 on a scale that remains invariant to the number of rating categories, producing ordered
208 rating category thresholds. For each item, MSD builds *L* different dichotomized matrices {D<sub>h</sub>:
209 1 ≤ *h* ≤ *L*} from the original rating scale data, where *L* is the total number of thresholds. D<sub>h</sub>
210 maps the observed response *r*<sub>ij</sub> of person *i* to item *j* to 0 if *r*<sub>ij</sub> < *h* and to 1 if *r*<sub>ij</sub> ≥ *h*, so that the
211 dichotomous Rasch model can be used for each D<sub>h</sub> to estimate a person measure for each
212 person *i* and an item measure for each item *j*. Final MSD-estimated person and item
213 measures are computed as the averages of the *L* different estimated person and item
214 measures, with the axis origin chosen by convention to be the mean item measure. The
215 analysis was conducted in the COMPASS and EXIST samples separately, using the R package
216 'msd' [43]. Prior to analysis, unidimensionality and local dependency conditions were
217 verified using a principal component analysis of the residuals and an assessment of residual
218 correlations between items, respectively; and a search for possible aberrant responses (i.e.,
219 responses incompatible with those expected by the Rasch model [44]) was carried out using
220 the R package 'PerFi't [45]. Mean-square item fit statistics were computed, using 'misfit'
function from 'msd' package, to assess the validity of each MSD model (COMPASS and EXIST), with expected values between 0.5 and 1.5 [46]. P-values were computed to assess the associated type I error rate, using the procedure described by Linacre [46]. We then compared estimated item measures in both samples, using the R-squared measure.

**Internal consistency.** A Person Separation Index (PSI) was computed from the previously defined MSD models, both in the COMPASS and EXIST samples, with a minimum desired value of 0.80 [47].

**Construct validity.** MSD-IRT models were computed for each scale used in the assessment of the EMoWI construct validity (Diener's FS, CESD-R, and GAD-7). We then examined correlations between estimated person measures for the EMoWI, and those of the three other scales, using Spearman's rank correlation coefficients. A positive correlation was expected between the EMoWI and Diener's FS since both measure similar concepts of well-being. In contrast, we expected negative correlations between the EMoWI estimated person measures and those of the CESD-R and GAD-7 scores, since previous research has shown that depression and anxiety are associated with low levels of well-being [48]. Given the different timeframes used by the scales (psychological "state" for the EMoWI vs. psychological "trait" for Diener's FS, CESD-R, and GAD-7), we expected to observe modest to moderate correlations between the scales [49].

**Measurement invariance.** The presence of potential Differential Item Functioning (DIF) was explored using the R lordif package [50] both on gender (after recoding response options as girl/boy/other) and nationality (Canadian/French). Consistent with work by Scott et al. [51,52], DIF detection was carried out by combining both test significance and measure of effect size, using the $\chi^2$ and pseudo-R-square statistics. We considered DIF effects as
244 significant only when the p-value was < 0.001 and the difference in R-square was > 0.02 for
245 non-uniform DIF, and when the p-value was < 0.001 and the absolute value of the log odds
246 ratio was > 0.64 for uniform DIF [50,52].

247 All analyses were conducted using R statistical software v4.0.3 [53].

248 Ethical considerations

249 All procedures related to the COMPASS study were approved by the University of Waterloo
250 Office of Research Ethics (ORE #30118), Brock University Research Ethics Board (REB #18-
251 099), and appropriate school board committees. A full description of the COMPASS study
252 methods is available online (https://uwaterloo.ca/compass-system/), or in print [24].

253 The EXIST project was registered by French regulations following reference methodology
254 MR004, in coordination with the Université de Lorraine Data Protection Office (no. 2021-
255 156). Prior to their participation, adolescents and their legal representatives were informed
256 in writing about the study and their right to refuse to participate or to ask to remove their
257 data at any time.

258 Results

259 *Study sample*

260 As part of the COMPASS study, the EMOWI was submitted to 2,504 Canadian adolescents
261 aged between 12 and 19 years old. Among the 2,504 adolescents who received the EMOWI,
262 2,212 (88.3%) responded to at least one item, and 1,838 (73.4%) completed all eight items of
263 the scale. Characteristics of the sample are described in Table 1. Most adolescents were of
264 white ethnicity and enrolled in Grades 9 or 10.
Description of the characteristics of the French sample used for ITT analyses is available in our previous report [16]. Most adolescents were 13 or 14 years old, and 52,5% identified as male.

<table><caption>Table 1. Characteristics of the study sample from the COMPASS study</caption><thead><tr><th>Characteristic</th><th>N = 2,504</th></tr></thead><tbody><tr><td><em>Age (years)</em></td><td></td></tr><tr><td>12 (or younger)</td><td>7 (0.3%)</td></tr><tr><td>13</td><td>4 (0.2%)</td></tr><tr><td>14</td><td>404 (16.1%)</td></tr><tr><td>15</td><td>793 (31.7%)</td></tr><tr><td>16</td><td>672 (26.8%)</td></tr><tr><td>17</td><td>429 (17.1%)</td></tr><tr><td>18</td><td>151 (6.0%)</td></tr><tr><td>19 (or older)</td><td>18 (0.7%)</td></tr><tr><td>Missing</td><td>26 (1.0%)</td></tr><tr><td><em>Grade</em></td><td></td></tr><tr><td>9</td><td>736 (29.4%)</td></tr><tr><td>10</td><td>762 (30.4%)</td></tr><tr><td>11</td><td>590 (23.6%)</td></tr><tr><td>12</td><td>390 (15.6%)</td></tr><tr><td>Missing</td><td>26 (1.0%)</td></tr><tr><td><em>Sex assigned at birth</em></td><td></td></tr><tr><td>Female</td><td>1,249 (49.9%)</td></tr><tr><td>Male</td><td>1,195 (47.7%)</td></tr><tr><td>I prefer not to say</td><td>26 (1.0%)</td></tr><tr><td>Missing</td><td>34 (1.4%)</td></tr><tr><td><em>Gender</em></td><td></td></tr></tbody></table>
<table><thead><tr><th>Characteristic</th><th>N = 2,504</th></tr></thead><tbody><tr><td>Girl/Woman</td><td>1,152 (46.0%)</td></tr><tr><td>Non-binary person</td><td>46 (1.8%)</td></tr><tr><td>Two-spirit</td><td>13 (0.5%)</td></tr><tr><td>Boy/Man</td><td>1,167 (46.6%)</td></tr><tr><td>I describe my gender differently</td><td>52 (2.1%)</td></tr><tr><td>I prefer not to say</td><td>42 (1.7%)</td></tr><tr><td>Missing</td><td>32 (1.3%)</td></tr></tbody></table>

### Ethnicity

<table><tr><td>I prefer not to say</td><td>27 (1.1%)</td></tr><tr><td>I do not know</td><td>49 (2.0%)</td></tr><tr><td>Multiethnic</td><td>196 (7.8%)</td></tr><tr><td>Black</td><td>72 (2.9%)</td></tr><tr><td>Asian</td><td>291 (11.6%)</td></tr><tr><td>Latino</td><td>52 (2.1%)</td></tr><tr><td>Middle Eastern</td><td>40 (1.6%)</td></tr><tr><td>White</td><td>1,670 (66.7%)</td></tr><tr><td>Another category</td><td>76 (3.0%)</td></tr><tr><td>Missing</td><td>31 (1.2%)</td></tr></table>

### SES Score

<table><tr><td>1</td><td>32 (1.3%)</td></tr><tr><td>2</td><td>124 (4.9%)</td></tr><tr><td>3</td><td>370 (14.8%)</td></tr><tr><td>4</td><td>949 (37.9%)</td></tr><tr><td>5</td><td>562 (22.4%)</td></tr><tr><td>Missing</td><td>467 (18.7%)</td></tr></table>
missing data (16.8% of participants); the item assessing stress had the lowest proportion (14.3%). There was no significant difference in participants' characteristics across non-respondents, partial-respondents, and complete-respondents (Table S1).

**Content validity.** While ceiling effects were observed for all items in the French version of the EMOWI [16], only two items (autonomy and safety) had a proportion of responses at the highest score above 15% (15.7% and 31.6%, respectively) in the English version. However, there was no floor or ceiling effects on the total score (Figure 2). The corresponding Wright map (Figure 3) showed a significant overlap between respondent ability range (around -2 to +3 logits) and item difficulty range (-2 to +2 logits), with a slight mismatch at the high end, suggesting a lack of differentiation for respondents with the highest scores in this sample.

**Fig. 2** Distribution of the EMOWI total score in the COMPASS sample (median score: 46.0 [IQR: 32.0–58.0])

<figure><img src="image_3.png" /></figure>
285

286

287

**Fig 3.** Wright map showing the distributions of person and item measures of the EMoWI in the COMPASS sample

<figure><img src="image_4.png" /></figure>

288

289

290

291

**Structural validity.** The hypothesis of unidimensionality was confirmed by the CFA with values above desired thresholds for all measures (CFI: 0.971, TLI: 0.959, RMSEA: 0.066). Standardized factor loadings were > 0.5 for all items.

292

293

294

**IRT modeling.** Both conditions of unidimensionality and local independency were verified in both samples (first factor eigenvalue = 4.29 in COMPASS, 3.9 in EXIST; difference between highest Yen's Q3 statistic and mean Q3 = 0.1785 in COMPASS, 0.19 in EXIST) [54].

295

296

297

298

Because the number of missing observations was relatively large, we removed incomplete cases before conducting the aberrant responders' detection, to prevent bias in the results [45]. Three participants (0.0014%) were flagged as aberrant responders. This proportion was considered negligible and the participants were retained for further analysis.
299 Fit indices in both samples were satisfactory for items 1 to 6. Indices for items 7 and 8 were
300 slightly lower, which may indicate a lack of variability in responses. Items 2 and 6 exhibited
301 statistically significant p-values in the COMPASS sample, but the associated item-fit statistics
302 were within the predefined acceptable range. R-squares between the estimated Canadian
303 and French item measures showed good concordance across samples (0.78 for items
304 measures, 0.86 for infit MSQ, and 0.79 for outfit MSQ).

<table><caption>305 Table 2. Mean-square item-fit statistics for the EMOWI in the Canadian COMPASS sample
306 and the French EXIST sample</caption><thead><tr><th></th><th>Item</th><th>Infit MSQ</th><th>p-value</th><th>Outfit MSQ</th><th>p-value</th><th>Item measure</th></tr></thead><tbody><tr><td rowspan="8">Canadian sample (COMPASS)</td><td>1</td><td>0.88</td><td>1.00</td><td>0.85</td><td>1.00</td><td>0.36</td></tr><tr><td>2</td><td>1.22</td><td>&lt; 0.001</td><td>1.18</td><td>&lt; 0.001</td><td>1.38</td></tr><tr><td>3</td><td>0.99</td><td>0.57</td><td>0.96</td><td>0.90</td><td>-0.25</td></tr><tr><td>4</td><td>0.92</td><td>1.00</td><td>0.88</td><td>1.00</td><td>1.17</td></tr><tr><td>5</td><td>0.88</td><td>1.00</td><td>0.85</td><td>1.00</td><td>-0.15</td></tr><tr><td>6</td><td>1.33</td><td>&lt;0.001</td><td>1.22</td><td>&lt;0.001</td><td>-2.11</td></tr><tr><td>7</td><td>0.54</td><td>1.00</td><td>0.52</td><td>1.00</td><td>-0.16</td></tr><tr><td>8</td><td>0.64</td><td>1.00</td><td>0.61</td><td>1.00</td><td>-0.24</td></tr></tbody></table><table><thead><tr><th></th><th>Item</th><th>Infit MSQ</th><th>p-value</th><th>Outfit MSQ</th><th>p-value</th><th>Item Measure</th></tr></thead><tbody><tr><td rowspan="8">French sample (EXIST)</td><td>1</td><td>0.79</td><td>1.00</td><td>0.68</td><td>1.00</td><td>0.14</td></tr><tr><td>2</td><td>1.15</td><td>0.03</td><td>1.09</td><td>0.10</td><td>0.28</td></tr><tr><td>3</td><td>0.97</td><td>0.66</td><td>0.82</td><td>1.00</td><td>-0.37</td></tr><tr><td>4</td><td>0.92</td><td>0.88</td><td>0.86</td><td>0.98</td><td>1.18</td></tr><tr><td>5</td><td>0.87</td><td>0.97</td><td>0.83</td><td>0.99</td><td>0.13</td></tr><tr><td>6</td><td>1.01</td><td>0.42</td><td>0.87</td><td>0.97</td><td>-1.06</td></tr><tr><td>7</td><td>0.61</td><td>1.00</td><td>0.52</td><td>1.00</td><td>-0.13</td></tr><tr><td>8</td><td>0.63</td><td>1.00</td><td>0.55</td><td>1.00</td><td>-0.16</td></tr></tbody></table>

307

308 *Internal consistency.* PSI was very satisfactory with a value of 0.874 in the Canadian
309 COMPASS sample, and 0.834 in the French EXIST sample.
**Construct validity.** As hypothesized, we observed a positive correlation, yet partial given the different timeframes, between the estimated person measures for the EMoWI, and those for Diener's FS (r = 0.39). Negative correlations were observed between the estimated item measures for the EMoWI and those for CESD-R (r = -0.50), and GAD-7 (r = -0.41). Person measures distributions for each of the four scales is presented in Figure 4.

Fig. 4: Distribution of Person Parameters Across Scales (EMoWI, Diener's FS, CESD-R, and GAD-7)

<figure><img src="image_5.png" /></figure>

**Measurement invariance.** Regarding gender, we observed a statistically significant (p < 0.001) DIF on items 1 (self-confidence), 2 (stress), and 6 (feeling of safety). For all three items, girls and adolescents identifying as other were less likely to score highly than boys. However, since none of these items met the magnitude criterion of log odds-ratio > 0.64, the DIF effect for these items can be considered non-significant.

Regarding country, we observed a statistically significant (p < 0.001) DIF on items 1 (self-confidence), 2 (stress), and 3 (loneliness). For all three items, Canadian adolescents were less likely than French adolescents to score highly. However, aligned with established DIF
326 thresholds, none of these items exceeded the log odds-ratio criterion of > 0.64, indicating
327 that the magnitude of DIF was negligible. This finding supports the hypothesis of
328 measurement invariance, and thus the appropriateness of combining or comparing the
329 English- and French-speaking samples.

330

331 **Discussion**

332 We reported on the initial validation of the English version of the EMOWI, the first scale
333 designed to measure momentary mental well-being in adolescents.

334 Cross-sectional psychometric properties assessed using data from a sample of over 2,000
335 Canadian adolescents drawn from the COMPASS study were highly satisfactory according to
336 both the Classical Test Theory and Item Response Theory, with high reliability and validity.

337 We showed that EMoWI items are well-targeted, as the distribution of respondents' abilities
338 closely matches the range of item difficulties, except at the highest ability levels. This is
339 probably related to the data collection methods used in the COMPASS study (i.e.,
340 adolescents responded during class hours, in a secure environment with little variability). It
341 is therefore likely that this discrepancy may be overestimated in the present study, in
342 comparison with ecological momentary data collection. While two items exhibited p-values
343 <0.05 for infit and outfit mean-square statistics in the COMPASS sample, the magnitude of
344 misfit, as evaluated by mean-square statistics, was negligible. It is important to consider
345 that, unlike mean-square statistics, type I error rates are very sensitive to sample size, and
346 can indicate a minor misfit that may not be practically significant [55]. This may explain why
347 we observed these results in the COMPASS sample, and not in the smaller EXIST sample.
348 These findings may also reflect the position of these items at the extreme ends of the latent
349 trait continuum, as shown in the Wright Map. Both items are central to the construct being
350 measured and are consistent with theoretical expectations, which justifies their inclusion
351 despite minor misfit. Overall, these results tend to confirm that the items included in the
352 EMOWI adequately measure people's level of well-being, supporting its construct validity.

353 Although statistically significant DIF was detected for numerous items for gender and
354 nationality, their negligible effect sizes are encouraging regarding measurement
355 equivalence. This opens up the possibility of comparisons both between Canadian and
356 French populations, and between genders. These results suggest that the EMOWI may be a
357 valid and reliable tool for measuring adolescents' momentary well-being, provided
358 additional analyses in real EMA context confirm these results.

359 Ecological Momentary Assessment allows researchers to accurately capture the day-to-day
360 experiences of subjects as they happen, offering a close-up view into their routines and the
361 variability of “process-by-person” interactions (i.e., how different adolescents react to
362 similar situations and exposures) [14]. The use of validated EMA tools, such as the EMOWI,
363 opens up promising opportunities for developing and implementing tailored mental health
364 EMIs in adolescents, especially those who are harder to reach through the traditional
365 healthcare system. When combined with location tracking, geographical EMA can also better
366 account for teenager's socio-geographical environments. As evidenced in a recent review by
367 Russell and Gajos, evaluations of the efficacy of EMIs in youth are lacking [14]. The
368 availability of instruments validated for momentary assessment could help address this gap.

369 Finally, to demonstrate the effectiveness of promising interventions and ensure their
370 transferability (i.e., “the extent to which the measured effectiveness of an applicable
371 intervention could be achieved in another setting” [56]), it is crucial to have measurement
372 tools that enable evaluation of these intervention in different contexts.
373 *Strengths*

374 Our study has several strengths. First, the translation process was based on validated
375 recommendations [23]. It involved a reconciliation process between two independent
376 translators, and an expert committee composed of members fluent in both languages.

377 Although our sample included students from only six Ontario schools, its characteristics,
378 particularly in terms of gender and ethnicity, resemble those reported in other studies using
379 data from the entire COMPASS cohort [38]. While the COMPASS study was not designed to
380 be representative, the full school samples, high response rates, and inclusion of varied
381 schools (e.g., in terms of regional income, urbanicity, etc.) supports generalizability [57].

382 Also, COMPASS results closely resemble a nationally representative study. The statistical
383 analysis plan followed the same steps as with the French version, ensuring high
384 comparability of the two versions of the EMOWI, and combined methods from both CTT and
385 IRT. Finally, we analyzed DIF, to ensure understanding of the latent construct was the same
386 in the French and Canadian contexts, providing an additional validity measure of the scale.

387 *Limits*

388 However, some limitations must be noted. As with our first report [16], this study did not
389 assess the psychometric properties of the EMOWI in an actual EMA context, which may
390 affect the utility of the findings in regard to reliability and sensitivity to change. Our main
391 aim was to evaluate the validity and reliability of the English version, before engaging in a
392 more intrusive data collection involving repeated measures, as is generally undertaken in
393 EMA. However, our results are encouraging and should serve as a basis for a further, more
394 complete evaluation of the psychometric properties of the EMOWI in a momentary setting.
395 Due to logistical considerations, it was not possible to take repeat measurements to assess
396 test-retest reliability of the EMoWI in the present study. However, results from our first
397 validation in the French EXIST sample showed high reliability (Intraclass Coefficient [ICC]:
398 0.83). Another limitation is the difference in contexts in which the evaluation was conducted
399 for the French and English versions. Both were carried out as part of broader research
400 projects (the EXIST project and the COMPASS study, respectively) and were submitted
401 among several other questionnaires. The online interaction with the scale was slightly
different in the two settings: French participants were presented one item per page, and had
402 to interact with the slider (i.e. provide an answer) to be able to go to the next item. Canadian
403 adolescents were presented with all items on the same page, and were free to answer any
404 number of items before going to the next page. This may explain why some DIF was
405 observed across samples. Notably, the highest proportion of missing data was noted for the
406 item measuring happiness. This item was perceived during qualitative interviews with French
407 adolescents as a broader and more complex construct, which needed more self-reflection
408 than other items and could therefore be more difficult to answer to. Furthermore, we are
409 unable to identify whether the DIF observed was related to the language (English vs. French),
410 the country of residence (Canada vs. France), the momentary cultural context (immediately
411 after the COVID-19 pandemic in EXIST vs. distant from the pandemic in COMPASS), or the
412 data collection methods, which limits our interpretation of measurement invariance. Further
413 research is thus needed to explore the impact of how the scale is implemented online (one
414 item per page, several items per page, ability to skip or not), and on its usability in
415 momentary settings.
416

417 Conclusions
418 The English version of the EMOWI has demonstrated promising reliability and validity for the
419 momentary assessment of well-being in English-speaking adolescents. Although an
420 evaluation of the scale psychometric properties in a momentary setting is needed, the
421 present results support the usefulness of the EMOWI in designing and evaluating ecological
422 momentary interventions in mental health, and, ultimately, make mental health
423 interventions more accessible.

424
425 **List of abbreviations**

426 CFA: Confirmatory Factor Analysis

427 CFI: Comparative Fit Index

428 COMPASS: Cannabis, Obesity, Mental health, Physical activity, Alcohol, Smoking, and

429 Sedentary behaviour

430 CTT: Classical Test Theory

431 DIF: Differential Item Functioning

432 EMA: Ecological Momentary Assessment

433 EMI: Ecological Momentary Intervention

434 EMOWI: Ecological Momentary Well-being Instrument

435 IRT: Item Response Theory

436 PSI: Person Separation Index

437 RMSEA: Root Mean Square Error of Approximation

438 TLI: Tucker-Lewis Index

439
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591
592
593

594 **Statements and Declarations**

595 *Funding*

596 The COMPASS study was supported by a bridge grant from the Canadian Institutes of Health

597 Research (CIHR) Institute of Nutrition, Metabolism and Diabetes (INMD) through the

598 "Obesity – Interventions to Prevent or Treat" priority funding awards (OOP-110788; awarded

599 to SL), an operating grant from the CIHR Institute of Population and Public Health (IPPH)

600 (MOP-114875; awarded to SL), a CIHR project grant (PJT-148562; awarded to SL), a CIHR

601 bridge grant (PJT-149092; awarded to KP/SL), a CIHR project grant (PJT-159693; awarded to

602 KP), a research funding arrangement with Health Canada (#1617-HQ-000012; contract

603 awarded to SL), a CIHR-Canadian Centre on Substance Use and Addiction (CCSA) team grant

604 (OF7 B1-PCPEGT 410-10-9633; awarded to SL), and by a project grant from the CIHR Institute

605 of Population and Public Health (IPPH) (PJT-180262; awarded to SL and KP). The COMPASS-

606 Quebec project additionally benefits from funding from the Ministère de la Santé et des

607 Services sociaux of the province of Québec, and the Direction régionale de santé publique du

608 CIUSSS de la Capitale-Nationale. KP is a Canada Research Chair in Child Health Equity and

609 Inclusion.

610 The EXIST project was funded by IResP and INCa as part of the call for research and

611 intervention projects to reduce and combat smoking (Grant IRESP-19-TABAC-V1-02).

612 The funders were not involved in the design or conduct of the study; collection,

613 management, analysis, or interpretation of the data; or preparation, review, or approval of

614 the manuscript.
615

616 *Competing Interests*

617 The authors report there are no competing interests to declare.

618

619 *Author Contributions*

620 **Marie Buzzi**: Methodology, Formal analysis, Writing – Original Draft

621 **Karen Patte**: Conceptualization, Resources (COMPASS study), Data Curation, Writing -

622 Review & Editing, Supervision, Project administration (COMPASS study), Funding acquisition

623 (COMPASS study)

624 **Yan Kestens**: Conceptualization, Methodology, Writing - Review & Editing

625 **Grégory Moullec**: Conceptualization, Methodology, Writing - Review & Editing

626 **Laetitia Minary**: Conceptualization, Resources (EXIST project), Writing - Review & Editing,

627 Supervision, Project administration (EXIST project), Funding acquisition (EXIST project)

628 **Jennifer O'Loughlin**: Conceptualization, Writing - Review & Editing

629 **Scott Leatherdale**: Conceptualization, Resources (COMPASS study), Data Curation, Writing -

630 Review & Editing, Supervision, Project administration (COMPASS study), Funding acquisition

631 (COMPASS study)

632 **Nelly Agrinier**: Conceptualization, Writing - Review & Editing, Supervision

633 **Jonathan Epstein**: Conceptualization, Methodology, Formal analysis, Writing - Review &

634 Editing

635
636 *Ethics approval*

637 All procedures related to the COMPASS study were approved by the University of Waterloo

638 Office of Research Ethics (ORE #30118), Brock University Research Ethics Board (REB #18-099), and appropriate school board committees. A full description of the COMPASS study methods is available online (https://uwaterloo.ca/compass-system/), or in print [24].

641 The EXIST project was registered by French regulations following reference methodology
642 MR004, in coordination with the Université de Lorraine Data Protection Office (no. 2021-
643 156). Prior to their participation, adolescents and their legal representatives were informed
644 in writing about the study and their right to refuse to participate or to ask to remove their
data at any time.
645