A validation of the construct and reliability of an emotional intelligence scale applied to nursing students1

OBJECTIVE: The current study aimed to validate the construct and reliability of an emotional intelligence scale. METHOD: The Trait Meta-Mood Scale-24 was applied to 349 nursing students. The process included content validation, which involved expert reviews, pilot testing, measurements of reliability using Cronbach's alpha, and factor analysis to corroborate the validity of the theoretical model's construct. RESULTS: Adequate Cronbach coefficients were obtained for all three dimensions, and factor analysis confirmed the scale's dimensions (perception, comprehension, and regulation). CONCLUSION: The Trait Meta-Mood Scale is a reliable and valid tool to measure the emotional intelligence of nursing students. Its use allows for accurate determinations of individuals' abilities to interpret and manage emotions. At the same time, this new construct is of potential importance for measurements in nursing leadership; educational, organizational, and personal improvements; and the establishment of effective relationships with patients.


Introduction
The concept of Emotional Intelligence (EI) surfaced several decades ago primarily through the work of Salovey and Mayer (1) . As it became more popular, several models and tools for the measurement of EI emerged.
In an effort to clarify this situation, the Encyclopedia of Applied Psychology suggested the existence of three major conceptual models ( (1,4) .
From this concept, Mayer and Salovey (4) designed one of the first measurement tools for EI, the 48item version of the Trait Meta-Mood Scale (TMMS), which resulted from a systematic literature review of the essential factors for the emotional and social functioning of individuals. Its multidimensionality was confirmed using factor analysis, which demonstrated that perception, comprehension, and regulation (with Cronbach alpha scores of 0.86, 0.87, and 0.82, respectively) were three theoretical factors that could be measured using this scale (4) . Prior studies have revealed excellent reliability and validity of results using shorter modified versions of the TMMS, which has been translated into several languages, including German (5) , Chinese (6) , Portuguese (7) , Persian (8) , Turkish (9) , and Basque (10) . A group of Spanish researchers (11) developed a valid adaptation of the TMMS that has been shown to have similar reliability and validity results of criterion and construct in successive applications in the Spanish population (12)(13) . After its development, this Spanish version has been used in several studies in Spanishspeaking Latin American countries (14)(15) , but not all authors report the validity and reliability levels obtained in their research.
Measuring this construct is especially relevant in the health field because the emotional dimension is a key factor in the area of personal interactions, where human care is manifested (16)(17) . Nursing is a profession that is particularly centered in this manner of care involving deep emotional connections. This specific characteristic of care leads nursing professionals to face complex situations that produce emotional reactions, such as high levels of anxiety, which they need to be able to manage effectively (12) . Thus, the ability to manage one's emotions and to interpret the emotions of others is especially useful in the performance of nursing functions.
Indeed, the capacity to evaluate and distinguish the emotional responses of patients can be decisive in the establishment of an efficient and significant relationship between the nursing professional and the individual receiving care (18) . Likewise, several studies have shown the importance of acquiring emotional abilities because of the fact that strong emotional skills can promote professional leadership, better interdisciplinary team work, and improved work satisfaction (19) . In contrast, poor management of emotional abilities can lead to professional deterioration and to worsening general health (20) .
It is particularly important for nursing students to begin learning how to interact with individuals in various health conditions, and they should thus be provided training in these abilities from the beginning of their educational program (21)(22) . Several studies that show the advantages and disadvantages of EI have reported that nursing students with better emotional abilities exhibit lower levels of anxiety regarding death (12,15,23) and a greater capacity for empathy (24) . Other studies have reported that lower emotional abilities are associated with increased stress levels, especially when exposed to clinical learning (25) , depressive behaviors, and low selfesteem (26) . It has also been suggested (21)

Methods
The psychometric evaluation process to assess validity and reliability was performed according to the literature recommendations (27) . The first step in Analyses of the test's reliability and construct validity were performed with the definitive sample, and these analyses took advantage of the fact that there were more than five elements per item of the scale (28) .
The reliability was examined by analyzing internal consistency using Cronbach's alpha reliability coefficient.
The optimal range of alpha values is generally considered to be between 0.7 and 0.9 (28) . The probability of error was set at 5%.
The validity of the EI construct was analyzed via confirmatory factor analysis, which made it possible to verify whether the factors and variables that made up the TMMS-24 scale were in congruence with the preestablished theory of tri-dimensionality (6) . The stages described in the next section were followed for this analysis (28) .
The correlation matrix between variables or scale items was created with the goal of reviewing the pattern of relationships between the variables (Pearson's r).
From this, we also obtained a series of statistical tests that indicate if the factor analysis is pertinent with the available information. For example, the Kaiser-Meyer- allowing for the confirmation of previously proposed theoretical constructs.

Participants
The sample consisted of 349 nursing students

Ethical aspects
Prior authorization to use the TMMS in this study

Emotional Intelligence Tool
The EI Scale, originally called the Trait Meta-Mood Scale (TMMS-24) by Salovey and Mayer (4) , which had been previously translated into Spanish, (11)

Results
Univariate analysis of the TMMS-24 scale demonstrates that the data are normally distributed. The scores obtained in all dimensions are within the range of adequate emotional perception, comprehension, and regulation, as shown in Table 1.    Regarding the data in Table 2

Factor analysis
The Kaiser-Meyer-Olkin test of appropriateness of the sample was 0.895, and the test of sphericity was significant (p<0.000), which allowed for a pertinent factor analysis. Saturations greater than 0.3 were gathered, and the criterion of using values greater than one was followed. The initial results prior to rotation ("I have a lot of energy when I feel happy") had a saturation <0.4, but its factor weight was more significantly oriented towards factor three. In turn, this same item was observed to have the lowest ability to explain the variability within its respective sub-scale (23%). The variability of the remaining items ranged between 41% and 71% (Table 4).

Discussion
The findings of this study highlight the strong reliability and construct validity of the TMMS-24 scale of EI in a population of Chilean nursing students, thus confirming the theoretical model proposed by the authors (1,4) .
With respect to the reliability of the EI scale, the results show that there is good internal consistency and homogeneity of the items. Specifically, this scale obtained a high level of reliability with Cronbach's alpha for each of the sub-scales, a finding that is similar to those reported previously in studies using the same tool in populations of nursing students, with Cronbach alpha values greater than 0.80 in all three dimensions (12,18) .
Similarly, a study of 451 Colombian adolescents obtained a Cronbach alpha for the TMMS-24 of 0.80 in perception, 0.76 in comprehension, and 0.75 in regulation (29) .
Likewise, the Portuguese version of the TMMS-24 applied to a sample of students obtained a Cronbach alpha of 0.80 for perception, 0.79 for comprehension, and 0.85 for regulation (7) .
In this sense, we can emphasize that the obtained by other researchers (13,30), , one of whom even suggested eliminating item 23 from the scale (30) along with item five, which was also observed to have lower (but still acceptable) correlation levels than the rest of the items from its respective dimension in this study.
In contrast, a different study (12) recommended keeping item 23 in the scale after verifying its effects in the model.
Other studies that have examined the construct validity of the TMMS-24 using factor structure have reported differing results, but this could be due to sampling differences. For example, an Australian study (31) initially identified four factors, but eventually confirmed only three factors after further confirmatory analysis. A Turkish study (32) also confirmed the factor structure, but the item distribution differed from that in the original study.

Conclusion
In conclusion, the tri-dimensionality and reliability of this scale are confirmed by the present results, which guarantee the quality of the tool in the studied population.
Based on the presented data, we can establish that the application of the TMMS-24 scale measures EI.  In addition, this scale has characteristics, such as its ease of application, which enables gathering responses from a large number of surveyed individuals.
Thus, this scale represents an easy and economical way to measure the EI construct.
However, we must consider the limitations of this study. The first is the fact that the questionnaire