The evaluation of the psychometric properties of the WASCOP Scale was based on a secondary data analysis of the Month 3 follow-up data from the Decídetexto study. Decídetexto is a randomized clinical trial that assessed the efficacy of a culturally accommodated mobile smoking cessation intervention among Latinos. Details of Decídetexto have been described elsewhere (Cartujano-Barrera et al., 2020, 2025). A Community Advisory Board composed of members from the Latino community provided guidance throughout the study’s design, implementation, and evaluation, ensuring the research remained aligned with community perspectives and priorities. Study procedures were approved and monitored by the Hackensack University Medical Center (#Pro2017-0528), the University of Kansas Medical Center (IRB #STUDY00004475), and the University of Rochester Medical Center (IRB #STUDY00005080) Institutional Review Boards. ClinicalTrials.gov identifier: NCT03586596.

Participants were recruited by Promotores de Salud (Community Health Workers) through community-based outreach and clinical settings. Detailed recruitment procedures have been described elsewhere (Arana-Chicas et al., 2021, 2022). Eligible individuals self-identified as Hispanic or Latino, knew how to read and speak English or Spanish, were at least 21 years of age, smoked cigarettes 3 or more days per week for at least 6 months, reported interest in quitting smoking in the next 30 days, had an active cellphone with unlimited text messaging capability, knew how to send and read text messages, and were willing to complete two study visits and assessments. Exclusion criteria included use of other tobacco products more than once per week; current participation in any other smoking cessation program or use of any medication to quit smoking; living with a current study participant; being pregnant, breastfeeding, or planning to become pregnant in the next year; or planning to move in the next 6 months. For this study, participants who completed at least 10 of the 12 WASCOP Scale items were included in the analysis, resulting in a sample of 374 participants.

Participants completed an in-person baseline survey and an over-the-phone follow-up survey at Month 3. All measures were available in English and Spanish and were administered by trained members of the research team. The baseline survey collected data on participants’ age, gender, educational attainment, preferred language, country or region of birth, and average number of cigarettes smoked per day. The Month 3 follow-up survey, administered to all participants regardless of randomization group, included the WASCOP Scale, the Smoking Self-Efficacy Questionnaire (SEQ-12), and a single-item measure of satisfaction with the smoking cessation program. The SEQ-12 is a validated 12-item instrument designed to assess an individual’s confidence in their ability to refrain from smoking across a range of different situations (Cartujano-Barrera et al., 2021; Etter et al., 2000). Each item is rated on a 5-point Likert scale, ranging from “Not at all sure” to “Absolutely sure.” Program satisfaction was assessed with the question “How satisfied are you with this smoking cessation program?” Responses ranged on a five-point scale from “extremely unsatisfied” to “extremely satisfied”.

The Working Alliance Inventory – Short Version (WAI-S) served as the foundation for the new WASCOP Scale. The WAI-S compromises 12 items, each rated on a 7-point Likert scale ranging from 1 (never) to 7 (always) (Hatcher and Gillaspy, 2006). The WAI-S is organized into three subscales: (a) Agreement on Goals, assessing the degree of concordance between the patient and therapist regarding the overarching treatment goals; (b) Agreement on Tasks, evaluating the extent to which the patient and therapist agree upon the tasks deemed necessary to achieve these goals and; (c) Bond Between Therapist and Client, measuring the emotional bond between the patient and therapist, encompassing elements of trust, acceptance, and attachment (Hatcher and Gillaspy, 2006).

In partnership with the Community Advisory Board, the WAI-S was adapted to reflect the structure of the Decídetexto study, in which participants did not interact with a traditional, face-to-face therapist. Instead, participants either received a mobile intervention or a printed educational material, which included information on accessing free behavioral counseling through their state quitline (Cartujano-Barrera et al., 2020, 2025). To ensure contextual relevance, the term “therapist” was replaced with “my smoking cessation program” throughout the scale.

A consensus approach was employed to translate the scale into Spanish. Two bilingual (English–Spanish) members of the research team independently translated the adapted English version of the scale. A third bilingual team member reviewed both translations, discussed any discrepancies with the translators, and facilitated the resolution of differences to reach consensus on the final Spanish version.

Simple frequencies were calculated for categorical variables and means and standard deviations for continuous variables. Internal consistency reliability of the WASCOP Scale was assessed using Cronbach’s alpha, with values greater than 0.90 indicating excellent reliability (Schmitt, 1996; Streiner, 2003). Item-total correlations were also assessed, with values below 0.30 indicating inadequate correlation with the overall scale (Ferketich, 1991; Henrysson, 1963). For factorial validity, the Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy and Bartlett’s Test of Sphericity were conducted to evaluate the suitability of the data for factor analysis. A KMO value greater than 0.60 was considered acceptable (Kaiser, 1974; Bartlett, 1937). Given the developmental nature of the WASCOP Scale, an exploratory factor analysis (EFA) was conducted to examine its underlying structure. Principal component extraction with varimax rotation was used to enhance interpretability. Factors were retained based on the Kaiser criterion, which recommends retaining components with eigenvalues greater than 1.0 (Kaiser, 1960). Factor loadings of 0.40 or higher were considered indicative of meaningful item-factor associations (Stevens, 2002). For convergent validity, Spearman’s correlation was conducted to assess the correlation between WASCOP Scale scores and study satisfaction. For discriminant validity, Spearman’s correlation was conducted to assess the correlation between WASCOP Scale scores and SEQ-12 scores. Missing data were handled using complete-case analysis. No imputation was performed. Analyses were performed using the Statistical Package for the Social Sciences v29.0 (SPSS; IBM Corp, 2022).

The Cronbach’s alpha coefficient for the total scale was 0.81. The item-total correlation matrix is detailed in Table 3. All items had item-total correlation values above 0.55, except for item 4 (0.159) and Item 10 (0.031). The overall Cronbach’s alpha decreased when Items 1, 2, 3, 5, 6, 7, 8, 9, or 11 were removed. In contrast, removing Item 4 or Item 10 increased the alpha to 0.85 and 0.86, respectively.

Internal consistency reliability was recalculated after removing items 4 and 10, resulting in an increased Cronbach’s alpha coefficient of 0.91 for the total scale. The new item-total correlation matrix is detailed in Table 4. All items had item-total correlation values above 0.55. Cronbach’s alpha coefficients did not increase with the removal of any additional items.

Construct validity of the 10-item scale (following the removal of items 4 and 10) was evaluated. The Kaiser-Meyer-Olkin measure of sampling adequacy was 0.92, indicating suitability for factor analysis. The Bartlett’s Test of Sphericity was significant (x² = 2191.75, d.f. = 45, p < 0.001), confirming that the correlation matrix was factorable. Two factors were extracted, explaining 38.31 and 19.16% of the variance, respectively. Together, the two factors accounted for 57.47% of the total variance. Items 3, 5, 6, 7, and 9 loaded on Factor 1. Items 1, 2, 8, and 12 loaded on Factor 2.

A moderate to strong positive correlation was observed between WASCOP Scale scores and study satisfaction (r = 0.530; p = 0.001). A weak to moderate positive correlation was observed between WASCOP Scale scores and SEQ-12 scores (r = 0.318; p = 0.001).

This study has several notable strengths. First, the sample size was appropriate for the psychometric analyses conducted. Second, the diversity among participants supports the relevance and applicability of the scale in the Latino community. Third, the availability of the scale in Spanish improves accessibility for Spanish-speaking individuals. Lastly, a Community Advisory Board was actively engaged in the development, implementation, and analysis phases, which strengthens the cultural appropriateness of the scale.

Despite the noted strengths, this study has some limitations that must be considered. First, the present study did not assess the predictive validity of the WASCOP Scale or its potential mediating role in smoking cessation outcomes. As this analysis focused on preliminary psychometric validation, future research should explore these dimensions to further establish the scale’s utility in intervention studies. Second, the analysis was not stratified by intervention arm. Half of the participants received a mobile smoking cessation intervention, while the other half received a printed educational material and access free behavioral counseling (Cartujano-Barrera et al., 2020, 2025). Given the distinct nature of these interventions, participants likely experienced varying levels of working alliance. However, the decision not to conduct separate analyses by intervention arm is appropriate for psychometric evaluation, as it captures a broader range of working alliance levels, thereby enhancing the robustness of the scale’s validation. Lastly, given that the WASCOP Scale was administered by the research team, there is a potential for social desirability bias among participants (Fisher, 1993). However, the research team administering the WASCOP Scale was distinct from the research team managing the mobile intervention, and participants were explicitly informed that they were free to express their honest opinions.