Relations of psychological characteristics and team performance level in female volleyball players aged 12 to 15 years (U15)

Aim: To validate the Psychological Skills Inventory for Sport – Youth (PSIS-Y) questionnaire on a sample of youth Croatian female volleyball players, and to determine psychological characteristics of players aged 12 to 15 years, as well as possible differences according to team (competitive) performance level in variables: motivation, self-confidence, anxiety control, mental preparation, team emphasis, and concentration.

Methods: The sample included 328 participants from 28 clubs competing at the national volleyball championship. We used the PSIS-Y questionnaire consisting of 44 items in 6 dimensions. Data analysis included validation of the questionnaire, descriptive parameters, and ANOVA to determine the differences in psychological dimensions between players at different performance levels, with the significance level set at P≤0.05. To determine the common effect of all the measured variables in differentiating the performance level between the groups of players, a multivariate procedure of discriminant analysis was used.
Results: The participants showed a high level of motivation, medium levels of concentration, self-confidence, anxiety control, and a low level of mental preparation. According to team performance level, significant differences were found in concentration (P=0.001), anxiety control (P=0.002), mental preparation (P=0.002), and motivation (P=0.034). The applied discriminant analysis yielded two statistically significant discriminant functions: the first function (χ2=27.54; P=0.002) differentiated the group of players with the highest index of team performance level from the groups with lower indices, whereas the second function (χ2=10.39; P=0.034) differentiated the group of players with the lowest index from the three more successful groups due to higher levels of motivation and anxiety control.
Conclusion: In comparison to previous findings, a decline in correlation between most psychological skills of youth female volleyball players and different levels of competitive team performance is noticed. This negative trend may be influenced by the increased importance of competition and an increased pressure put on youth players by their environment.

Introduction
Volleyball is a team sports game available to everyone. It is part of the curricular and extracurricular program of physical education for students of both elementary schools and high schools and it is gaining popularity as a student sport and recreational activity, especially among the female population (Milić, 2014). The objective of volleyball is to send the ball over the net with no more than three touches (between members of the same team) and ground it on the opponent's field, or to take advantage of the opponent making a mistake, thus winning a point (Grgantov, 2005). This can be achieved only in a positive and stimulating team environment, defined by the harmony between team members and the coach, which is the main requirement for team functioning. To achieve these sports goals, it is necessary to involve a sports psychologist, whose task is to educate and help the coach in shaping the desirable patterns of the motivational climate, to nurture open communication and interpersonal relationships in terms of acceptance and care for one's teammates (Orlick & Partington, 1988).
It is a fact that athletes in team sports are forced to spend the majority of their time as part of the group, which does not necessarily mean that they like spending time with their colleagues, or are all compatible as persons. Many studies have proven that team motivational climate and cohesiveness greatly determine athlete's motivation and athletic achievement (Orlick & Partington, 1988;Alexander & Krane, 1996;Cox, Russell & Robb, 1999;Duda, 2001;Roberts, 2001;Jurko, 2013;Milavić, 2013;Galić, Protić, Žvan & Kondrič, 2014;Stanović, 2017;Stanović, Milić & Grgantov, 2020). Furthermore, in sports practice, top athletic achievements or unexpectedly poor achievements are often attributed to athletes' psychological skills (Stipkov, 2018). A "positive" example of pronounced psychological skills is an athlete or a sports team that does not exhibit particular characteristics of success during training or preparation but achieves exceptional success or success above expected during an important competition. A possible "negative" example is an athlete or a sports team with a high level of sports achievement and great success during training who cannot reproduce that level of success in a competition (Stanović, 2017). Orlick and Partington (1988) state that a crucial difference between successful and less successful athletes at the elite level is their difference in mental and psychological skills, emphasizing that by the acquisition of necessary skills and techniques, an athlete can not only achieve some of the sports goals more easily but also achieve higher levels of personal success and joy of living.
Furthermore, on a sample of youth and junior female volleyball players, Milavić, Grgantov, and Veličkovska (2013) determined no significant differences in the level of psychological characteristics between groups of players playing at different positions within their team.
They measured psychological characteristics with the Athletic Coping Skills Inventory (ACSI-28), constructed by Smith, Schutz, Smoll, and Ptacek (1995). As opposed to ACSI-28, the Psychology Skills Inventory for Sports -Youth version (PSYS-Y), constructed by Elferink-Gemser (2005), was developed to measure the psychological skills of young athletes -distinguishing between more talented and less talented young athletes. The questionnaire measures six dimensions: mental preparation, motivation, concentration, self-confidence, team emphasis, and anxiety control. This measuring instrument differentiates male and female athletes, individual and team sports athletes, and groups of athletes with different athletic skill levels (Milavić, 2013). Sindik, Novokmet, and Havaš-Auguštin (2013), Milavić, Jurko, and Grgantov (2013), and Sindik (2014) used the PSIS-Y questionnaire in their studies and, by using factorial structure, determined satisfactory reliability in youth Croatian table tennis players and youth male and female volleyball players. Stipkov (2018) and Milavić (2013) used the PSIS-Y on a sample of youth and junior female volleyball players and confirmed satisfactory metric characteristics for five of the total six scales of the questionnaire. The team emphasis scale had an inadequate level of reliability.
A new problem is imposed: will a repeated measurement by applying factor analysis after a certain time interval on a large sample confirm previous findings on reliability and sensitivity of the PSIS-Y, and what multiple effect will it have on the competitive success of youth Croatian volleyball players? The aim of this study was to determine psychological characteristics of youth female volleyball players aged 12 to 15 years, and the possible differences according to team (competitive) performance level in variables motivation, self-confidence, anxiety control, mental preparation, team emphasis, and concentration, and to validate the PSIS-Y questionnaire on a sample of youth Croatian female volleyball players.

Participants and methods
The sample included 328 youth female volleyball players aged 12 to 15 years (U15), members of 28 clubs from all Croatian regions, participating at the open national volleyball championship. To make the sample as representative as possible, volleyball players from all regions were included, especially members of the best clubs at the national level.
All players from the 7 best-ranked clubs, i.e., 76 players, participated in this study, as the group of most successful players, with Index 4. The second group included 89 players from 8 clubs ranked between 8th and 15th place, representing the group of more successful players, with Index 3. The third group included 77 players from 7 volleyball clubs ranked from 16th to 23rd place at the youth national championship, representing the group of less successful players with Index 2. The group of least successful players is represented by 86 volleyball players from 8 clubs ranked between 24th and 32nd place at the youth Croatian volleyball championship (U15).
Participants' mean chronological age was 14.62±0.71 years, whereas their mean training age was 36.44±15.32 months. Participants' mean body height was 172.05±6.18 cm, and their mean body mass was 57.52±8.79 kg. All subjects had ID cards provided by the Croatian Volleyball Federation and verified by an authorized sports physician.
The variable sample included the items of the PSIS-Y, by Elferink-Gemser et al. (2005), which consists of 44 statements and measures 6 dimensions: motivation, self-confidence, anxiety control, mental preparation, team emphasis, and concentration. The scale is a 5-point Likert-type scale with levels of assessment ranging from 1 -I strongly disagree to 5 -I strongly agree.
There was one dependent, i.e., grouping variable defined in this study: Competitive (team) success of players was determined by team placement among the 32 youth volleyball teams that participated at the open Croatian championship.

Description of the experimental procedure
In the first phase of the research, the date of the survey was set in agreement with the responsible persons from the volleyball clubs (Youth National Volleyball Championship).
The coaches informed the players' parents about the reasons for conducting the research and obtained written consent for their underage children to participate in the research.
Besides parental consent, permission to conduct the research during the national championship was also obtained from the umbrella organization, the Croatian Volleyball Federation.
In the second phase, the PSIS-Y questionnaire was filled out the day before the national championship in Rovinj started. The participants filled out the questionnaire in sports halls and the researcher emphasized the importance of answering honestly. In case some of the participants needed help when filling out the questionnaire or asked for some additional information, the researcher was available at all times.
In the final phase, team success was assessed based on the results achieved in the Youth National Volleyball Championship (Official website of the Croatian Volleyball Federation, competition results). The collected data were analyzed using the Statistica Ver. 13.00 (StatSoft, SAD) computer program.

Methods of data analysis
Data analysis included validation of the applied questionnaire and analysis of metric characteristics of variables: motivation, self-confidence, anxiety control, mental preparation, and concentration, on a sample of youth female volleyball players. Basic metric characteristics of the scales were calculated: reliability -coefficient of internal consistency Cronbach's alpha, total explained variance, and sensitivity -coefficients of asymmetry Univariate analysis of variance (ANOVA) was used to determine the differences in motivation, self-confidence, anxiety control, mental preparation, team emphasis, and concentration between players with different competitive performance, with the significance level set at P≤0.05.
To determine the common multivariate "effect" of all the measured variables in possible differentiation of competitive success between groups of players, a multivariate procedure of discriminant analysis was applied.

Results
The results of validation of the scales of the PSIS-Y questionnaire by using factor analysis are presented in Tables 1-6.  After selecting one statement (item), a satisfactory coefficient of reliability Cronbach's alpha of 0.73 was obtained for the motivation scale, whereas the total explained variance was 57.54% (Table 1).
A satisfactory Cronbach's alpha coefficient of reliability of 0.73 was obtained for the self-confidence scale, whereas the total explained variance was 54.65% ( Table 2).

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A good coefficient of reliability Cronbach's alpha of 0.80 was obtained for the anxiety control scale, whereas the total explained variance was 42.68%. A good coefficient of reliability Cronbach's alpha of 0.79 was obtained for the mental preparation scale, whereas the total explained variance was 48.54%. After selecting one item, an unacceptable coefficient of reliability Cronbach's alpha of 0.36 was obtained for the team emphasis scale, whereas the total explained variance was 25.29%; thus, the scale was excluded from further analysis. After selecting one item, a satisfactory coefficient of reliability Cronbach's alpha of 0.72 was obtained for the concentration scale, whereas the total explained variance was 60.08%.
Descriptive statistics parameters of 5 validated and acceptable scales of the PSIS-Y questionnaire are presented in Table 7.  Table 7, the scales of motivation, self-confidence, and concentration had sat- The results of the analysis of differences (ANOVA) in psychological skills between the groups of youth players at different levels of team performance are presented in Table 8. By applying univariate analysis of variance on four groups of players at different levels of team performance, significant differences were found in four of the five measured psychological skills: concentration (P=0.001), anxiety control (P=0.002), mental preparation (P=0.002), and motivation (P=0.034). There were no significant differences between these groups of players in the self-confidence variable.

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The discriminant analysis results of psychological skills between groups of youth players at different levels of team performance are presented in Table 9. Multivariate discriminant analysis on a predictor set of psychological skills, with the aim to discriminate between groups of youth female volleyball players at different levels of team performance, yielded two statistically significant discriminant functions.
The first function discriminates the group of players at the second level, who have a higher team performance level, from the other three groups of players with lower indices of team performance and the highest level of team performance. By examining group centroids (group's projection on the discriminant function), it was determined that the two groups of more successful players were highly differentiated from the two groups of less successful players.
The group of players with the highest team performance index is characterized by a high level of difficulties with concentration (-0.78) and a higher level of anxiety (-0.58).
Furthermore, more successful players are defined by a high level of mental preparation coefficient (0.70), which indicates they are more mentally ready to play than the other groups of young players.
The second function discriminates the group of less successful players from the other three groups of players. The group of less successful players is quantitatively characterized by higher levels of motivation (0.56) and anxiety, as the scale is inverted, negatively oriented (-0.55).

Discussion
By applying univariate analysis of variance on four groups of players at different levels of team performance, significant differences were found in four of the five measured psychological skills: concentration (P=0.001), anxiety control (P=0.002), mental preparation (P=0.002), and motivation (P=0.034). There were no significant differences between these groups of players in the self-confidence variable.
It can be assumed that a higher level of the previous success of players from the most successful teams leads to higher expectations regarding athletic results of those teams, which may put the players under higher pressure which they cannot easily "control". Hence, they exhibit higher levels of anxiety. It is also possible that in the most successful teams, precisely because of those high expectations within the team, there is a form of rivalry or a lower level of cohesion. Thus, the players are more anxious and worried about their performance. As team cohesion was not measured in this study, it is merely a speculation, which can be the subject of future studies, but the basis for this speculation is Cox's (1987Cox's ( , 2005 statement that state anxiety of athletes in teams that exhibit higher levels of cohesion is significantly lower than in teams with lower levels of cohesion. Hence, if a team achieves high levels of cohesion, all the players in that team will play more freely and with fewer reactions of their teammates on their possible mistakes. Generally, by observing the overall anxiety results in all four groups, it can be stated that anxiety control is not high, and it is necessary to work more on players' anxiety control in all the groups. The other psychological variables (motivation, self-confidence, anxiety control, and mental preparation) are much lower in older age groups. Considering this is a cross-sectional study, causation between the analyzed variables cannot be determined. The possible reasons could be that in older age groups teams have already been selected, i.e., players are better specialized for their playing role, the competition between players is much stronger, and expectations are much higher (players are expected to perform at the top level, with very few mistakes due to poor performance of volleyball elements).
Multivariate discriminant analysis on a predictor set of psychological skills, with the aim to discriminate between groups of youth female volleyball players at different levels of team performance, yielded two statistically significant discriminant functions. The first function discriminates the group of players at the second level, who have a higher team performance level, from the other three groups of players with lower indices of team performance and the highest level of team performance. By examining group centroids (group's projection on the discriminant function), it was determined that the two groups of more successful players were highly differentiated from the two groups of less successful players. The group of players with the highest index of team performance is characterized by a high level of difficulties with concentration and a higher level of anxiety, i.e., greater feeling of pressure which cannot be controlled. The second function discriminates the group of less successful players from the other three groups of players. The group of less successful players is quantitatively characterized by higher levels of motivation and anxiety. These results are congruent with previous findings of Stipkov (2018), who conducted the study also on the sample of youth female volleyball players of approximately the same chronological age, and Milavić (2013), who performed research on male and female volleyball players with somewhat higher chronological age and found lower quantitative values of the measured dimensions.
The scientific contribution of this paper is the validation of the measuring instrument on a large sample of participants and the confirmation of previous findings on the psychological skills of youth female volleyball players. To properly understand the causal relationship between the analyzed psychological variables and competitive performance, it is necessary to conduct experiments to determine how changes in a psychological skill affect competitive performance and how changes in competitive performance affect psychological skills. By comparing the results of this study with previous studies investigating this problem, a decline in the level of correlation between most psychological skills of youth female volleyball players and different levels of competitive team performance is noticed.
This negative trend may be influenced by the increased importance of competition and an increasing pressure put on youth players by their environment, and it should be investigated further. If it is established that the increased pressure from the environment actually does affect the decline of psychological skills, it will be necessary to work systematically on multiple levels to change that. The first level is to act educationally on persons who turn out to be the cause of stress (parents, coaches, club management), to relieve or eliminate the "source" of stress. The second level is to develop stress coping skills in youth female volleyball players, i.e., to develop psychological skills that could improve performance in a competition.
All of the above emphasizes the necessity of developing these psychological skills in youth players, but also of systematic work of the expert team, which should certainly include a sports psychologist.