DETERMINING DIFFERENCES BETWEEN JUNIOR PLAYERS IN PARTICULAR POSITIONS IN THE BASKETBALL GAME AND BASED ON INDICATORS OF SITUATIONAL EFFICACY

The basic goal of this research was to determine the differences between junior players playing particular positions in the basketball game based on the indicators of situational effi cacy. The sample of examinees consisted of 108 top-level junior basketball players who in average played a minimum of 8 minutes per game and in more than 3 games, and were chosen from 11 teams that played 46 games in the Junior European Championship in Zadar in year 2000. The results show discrepancies in the space of situational effi cacy amongst 5 player positions, as follows: players who play the point guard and the shooting guard are dominant in variables SHOT3-SU, SHOT3-UN, ASSIST, ST and TO. The players who play the position of forward are dominant in variables SHOT2-SU and SHOT2-UN, especially in relation to the power forward and point guard and the shooting guard. Furthermore, the players who play centres can best be distinguished from those playing other positions in variables: DR, OR, BL, SHOT2SU i PF. We suggest that further research also includes nonstandard parameters of situational effi cacy when analysing differences between elite junior and senior players who play different positions in the game


INTRODUCTION
Basketball is a sport of contradictions in which at the same time exist a game tactics model and an infi nite number of possibilities for resolving game situations, and on the level of basketball teams there is a model of cooperation and confrontation (Hernandez, 1987;Gréhaigne, & Godbout, 1995), and therefore it requires skill to achieve harmony between individual and team goals, that is, between individual and team situation solving in the game (Trninić, Perica & Dizdar, 1999;Trninić & Dizdar, 2000; Gréhaigne, Bouthier, & Godbout, 1997).
Situational indicators of game success are functionally and inseparably connected.Limiting to indicators of situational effi cacy, and neglecting the process of interaction during the basketball game, is an unacceptable way of explaining facts.The research showed (Trninić et al, 1995;Swalgin, 1994) that not all indicators of situational effi cacy have the same infl uence on the fi nal outcome of the game or are of the same diffi culty for all positions in the game (Trninić & Dizdar, 2000).From the aspect of the general situational approach, we may say that there are one-dimensional and poly-dimensional criterion for a particular position and role in the game.
Thus the one-dimensional criteria are the measures in which player reactions can be defi ned with one single variable (e.g.blockshot, shot from the free-throw line), and the poly-dimensional criteria are the measures in which the elements of situational success are assessed from more reactional aspects in the game (e.g.pressure level in defence, defensive help, ability to play multiple positions).
Back in 1941, Ebell and Allen (1941) tried to make a better assessment of individual and team effi cacy based on registering events in the game (a much more detailed register than the one provided by offi cial game statistics) that have a positive or a negative infl uence (success and defeat factors) on the game's fi nal score.Each factor was subjectively rated with scores that express the importance of particular events in relation to their contribution to success.Unfortunately, no data was collected from the games of opposing teams during matches, nor was the procedure of data acquiring done consistently during three seasons of competition.The authors concluded that many events or effi cacy factors occur on games, and therefore it is quite certain they infl uence the fi nal outcome of the games, and consequently reveal the cause of victory or defeat.
Therefore they believe that the proposed model can be used for evaluation of the effi cacy of particular player and team.It is important to note that the authors clearly differentiated the individual from the team aspect of the game (one player's contribution to situational effi cacy of teammates).Such an approach enables a higher quality analysis of a game of basketball.
Accordingly, player types can be defi ned as groups of players with similar dominant features and characteristics that enable their playing effi cacy in one, two or more roles in the game.We can distinguish three types of players: guards, forwards and centres.Besides the main three types of players, there are subtypes, for example the point guard, shooting guard and the power forward.The player under the infl uence of adequate sports preparation, experience in competitions, and quality can easily cross over from one type to another, and thereby change the roles in the game (Trninić, 2006).
Roles inside the game are made of motor activities and behaviours that are expected from a particular player and which he realises at a certain position of precise rights (authorities), responsibilities and tasks, i.e. what the particular player is required to do (Trninić, Perica & Pavičić 1994;Trninić, 1995).In top-level basketball "the amount of authority simply must be covered by the same amount of responsibility" (Nikolić, 1993).Player roles in certain positions are interconnected and inter-complementing in a particular game tactics model (Trninić, 1995;Dizdar, 2002;Trninić, Dizdar & Dežman, 2000;Dežman, Trninić & Dizdar, 2001a, 2001b).
This way a game of basketball can be explained through a description of each player type's tasks.In his position inside his role, each basketball player has an individual task structure considering the appointed game concept.This structure can be meaningfully described, and the tasks listed (Trninić, 1995(Trninić, , 1996;;Trninić, Trninić & Jelaska 2010).It is important to point out that the basic indicators of player effi cacy are not enough to describe the complex structure of a game of basketball, nor are they a norm for determining the level of quality and preparation of players and teams.Therefore, in the situational approach, and in the context of sports science, the derived variables of player effi cacy in offence, defence and total are calculated from basic indicators of player effi cacy (Dežman, 1979;Dežman, 1992aDežman, , 1992b;;Kurent, 1998;Lidor & Arnon, 2000;Dizdar, 2002;Dežman, Erčulj & Vučković, 2002).
Thus the derived indicators show absolute and relative effi cacy.The indicators of absolute player effi cacy reveal data on all successful actions in offence, defence and/or overall that directly infl uence the game score, and the indicators of relative effi cacy show the relationship between successful and all offence, defence or overall actions.Results obtained from the indicators of absolute and relative effi cacy complement each other.Swalgin (1994) after having carried out a three-year study at Men's division college at an American university using basketball players, established the norms for the assessment of the situational effi cacy of basketball players according to the positions they played and their playing time.He designed an effi ciency-related computer programme for the assessment of basketball players whereby positive and negative sides of the game of each player based on his position and role in the game.
Based on the mentioned system for rating effectiveness of players, the author studied connections between the unweighted and weighted systems with assessments of player effi cacy provided by other experts.The results indicated that both methods are highly connected to coach's assessments of players' situational effi cacy.The results also show that the four indicators of player effi cacy distinguish separate game positions: defensive and offensive rebounds and blockshots best separate centres from guards and forwards, assistances signifi cantly differentiate guards from forwards and centres, while the three-point shot separates guards and forwards from centres.
Trninić, Dizdar & Jaklinović-Fressl (1999) tried to determine and explain the differences between players who primarily play positions 1 -playmaker, 2 -shooting guard, 3 -small forward, 4 -power forward and 5 -centre, using 13 indicators of situational effi cacy.For reaching this goal they used a sample of 60 basketball players who during the competition season 1998/99 of the fi rst Croatian basketball league played at least 10 minutes per game in 10 games.The results of the discriminative analysis confi rmed the hypothesis on differences between players considering their primary role in the game, and enable a fuller description of players.Jeličić, Trninić and Jelaska (2010) established the latent structure of situational effi ciency of elite junior basketball players.
For this purpose, on a sample of 108 elite junior basketball players, participants of the 19th Junior European Championship in Zadar in 2000, they applied the exploratory factor analysis strategy by use of the principal components method on the standard 13 indicators of situational effi cacy of the basket-ball game.Hereby two relatively independent latent dimensions have been isolated and named as: situational technical-tactical activity factor of the inside players (SEFOP) and situational technical-tactical activity factor of the outside players (SEFIP).
The mentioned two latent dimensions use 64% of total variance of manifest space, out of which the fi rst latent dimension uses 40% and the second uses 24% of the total variance.These percentages are relatively high and understandable considering the structure of correlation matrix.
The fi rst signifi cant factor describes 40% of the total variance of the system of applied variables for assessment of situational effi cacy, and it has obvious correlations with variables SHOT1-SU, SHOT1-UN, DR, OR, PF and BL.
Thus the fi rst signifi cant factor describes 40% of the total applied variables system for the evaluation of situational effi ciency and it has marked correlations with FT1-SU, FT1-UN, DR, OR, PF and BL variables.Therefore, one can talk about the factor of inside players' situational activity, i.e., their game tasks, which are evident in situational effi ciency variables that determine the latent dimension of technical-tactical activity of inside players at a competition.Presumably, at the stated factor are positively projected players who play on positions 4 and 5, and whose organization of defensive and offensive activities is primarily in the restricted area (Jeličić, Trninić i Jelaska, 2010).
Furthermore, the second signifi cant factor describes 24% of the total system variance and highly correlates with SHOT3-SU, SHOT3-UN, A and ST variables.The other signifi cant factor highly correlates with variables SHOT3-SU, SHOT3-UN, ASSIST and TO, so in this case one can talk about a factor that accounts for the technical-tactical activities of outside players.It is because tasks in the stages of transitional and positional defence performed by outside players (ball pressure and passing lines in the front defensive line) determine a bigger number of steals.On the other hand, the activities of players in the back offensive line open the possibilities for shooting beyond the 6,25 line and passing the ball which precedes selective shotsassists that increase offense effi ciency.
According to the acquired results, it is assumed that not even the usually used variables of situational effi cacy, as well as their deriving latent dimensions, do not suffi ce to completely explain the structure of the basketball game.
The aim of this research was to establish and explain the difference in manifest variables for evaluating situational effi cacy between players who play different positions (1 -point guard, 2 -shooting guard, 3 -small forward, 4 -power forward, 5 -centre) thus using discriminant analysis of manifest structure of 13 standard parameters of situational effi cacy.
The basic problem of this paper is to substantiate or refute the differences between players of junior and senior age according to basic player types (guards, forwards and centres) in basketball.

METHOD Entity sample
The sample is composed of 108 elite junior basketball players (42 guards, 26 forwards and 40 centres), participants of the 19 th Junior European Championship in Zadar in 2000.Out of the total number of players, only those who played averagely more than 8 minutes per game and who played 3 or more matches were included in the sample, from the total of 11 teams who played 46 games of the Junior European Championship (Table 1).
The players are, according to the data from offi cial tournament application forms, assorted into 5 groups based on usual positions in which they play: 21 player in position 1 (point guard), 20 players in position 2 (shooting guard), 26 players in position 3 (small forward), 24 players in position 4 (power forward), and 17 players who dominantly played position 5 (centre).Basketball players' average age was 17,8 (± 0,7σ).All examinees gave their consent for participating in the survey, in accordance with FIBA's approval.This represents a model sample of the best junior basketball players in Europe.

Variable sample
The sample of manifest variables is made out of 13 standard indicators of situational effi cacy in a game of basketball that are as default registered for every team in the match.These are: The collected data is the offi cial statistics recorded at every match according to the rules of the technical commission of FIBA.The data regarding the basketball results in the computer programmes designed for keeping statistic scores on basketball games has been registered by persons (statisticians) specially trained for the job.

Data processing methods
For each of 5 player groups the parameters of descriptive statistics have been calculated: arithmetic mean (AM), minimum score (Min), maximum score (Max), standard deviation (SD), Skewness (Skew), Kurtosis (Kurt).Furthermore, a discriminant canonical analysis was conducted on the mentioned fi ve homogeneous player groups -positions, for manifest and latent space in 13 variables of situational efficacy, and thus calculated: the coeffi cient of canonical correlation (Can R), Wilks Lambda (WL), the relevance level (P), position of group centroids (C), and provided with a structure of signifi cant discriminant functions (DF).

RESULTS AND DISCUSSION
In Table 2, a presentation of descriptive statistics indicators of situational effi cacy variables is given on a sample of 108 elite junior European basketball players.Furthermore, considering there is no need to explain measures of central tendencies in detail, what will be analysed are the measures of symmetry and fl atness of results distribution, which also inform on the sensitivity of particular measuring instruments.
Mildly negative value is seen in variable PF (Kurtosis = -0,73).Somewhat more test sensitive were the variables SHOT2-SU, TO, and SHOT3-UN whose Kurtosis values go between 1,23 and 1,69.Accentuated Kurtosis values are visible in variables SHOT3-SU (Kurtosis = 2,02) and TO (Kurtosis = 2,35).High Kurtosis values on the overall sample, that at the same time warn about high sensitivity of tests, are visible in variables SHOT1-UN (Kurtosis = 6,61), ASSIST (Kurtosis = 7,48) and BL (Kurtosis =4,43).Furthermore, Table 3 shows descriptive statistic indicators for all 5 positions, and in accordance with the goal to precisely represent situational effi cacy of quality basketball players of junior age.It must be emphasised that all variables are normally distributed in the total sample and divided into 5 positions.In Table 3 it is shown that the players who primarily play position 1 -guard playmaker, and differ from others mostly based of a larger number of assists, turnovers and steals.This is in accordance with their primary role in transition and set offence, which is seen in direct setting up the play, and involves ball control, timely and accurate passes to teammates in the most favourable positions for realisation, control in change of game pace and rhythm, restoring balance in the game, etc.In transition defence and set defence the playmaker directly determines the level of pressure.Besides that, those players have a much higher score of three-point shots then the centres (po-sitions 4 and 5) and somewhat higher then players in positions 2 and 3, which means that the point guard must have a scoring mentality.
Additionally, the players who primarily play position 2 -shooting guard, in contrast to players playing position 1, have slightly less three-point shots, defensive rebounds and slightly more offensive rebounds, less assists, steals and turnovers.Furthermore, they are dominant over the point guards in variables PF, SHOT1-SU and SHOT1-UN.They are extremely different from the power forward and the centre (position 4 and 5) in terms of more threepoint shots, and less defensive rebounds, offensive rebounds and blockshots.
Acquired results show that the players who primarily play position 3 -small forward, almost in all variables emerge between the guards (playing positions 1 and 2), and the 4 and 5 (the power forward and the centre).They differ from the guards by having a lesser number of three-point shots, but a bit more rebounds and blockshots.This position in the middle of other players is understandable since the players in position 3 change their position in the fi eld from inside to outside and vice versa, that is, they play facing and back-toward the basket, which puts them in a favourable position for shooting from inside and outside positions.Compared to the guards, the small forward gets into more situations where he is the nearest to the basket (post-up manoeuvres), and often has the best position to achieve a two-point goal and an offensive rebound, which enables him to be a more effi cient jumper than the guards.
Players in position 4 -power forward, differ from players in position 5 in the three-point fi eld goal variable.Notably, the players in position 4, unlike classic centres (position 5), who are mainly engaging in the post (or low block) position, have a greater movement radius (between the guard and the low and high post), and they attempt shots from halfdistance and full distance, penetrate facing the basket and more often open up to receive the ball.All this makes them crucial for opening space for an inside game, as well as cuts and offensive rebounds from the background.
The players who primarily play position 5centre, account for many more rebounds, blockshots, personal fouls and two-point fi eld goals then the players in other positions.The centres have an anchor role in team defence (control of the key and the jump).Considering this role, they make more personal fouls than guards and forwards.
Manifest variables for assessment of situational effi cacy on the fi rst function are positively or negatively correlated to the discriminant function, except the variables SHOT1-SU and SHOT1-UN, which are characterised by a ''zero'' correlation to the discriminant function.Most prominent correlations with a negative prefi x were found with variables: SHOT3-SU, SHOT3-UN, ASSIST, TO and ST.Largest positive correlation to the fi rst discriminant function is found in variables BL and OR.The rest of the variables are less correlated to the fi rst relevant discriminant function, so they won't be additionally explored.
According to the formerly defi ned position of group centroids, it can be said that the players who play guard positions are absolutely dominant in variables SHOT3-SU, SHOT3-UN, ASSIST, TO and ST, and primarily in contrast to the centres, but also power forwards.Their dominance in this structure of variables for assessment of situational effi cacy is also relevant when compared to the small forwards.The differences between small forwards and power forwards plus centres are also visible in the mentioned variables.Centres and power forwards are, however, dominant in variables that positively correlate to the function (BL and OR), which is in complete accordance with their roles and assignments in the game.
The second discriminant function actually distinguishes small forwards from all other player positions.According to the position of centroids for the fi ve player positions, it can be concluded that the players who play positions of the small forwards are totally dominant in variables SHOT2-SU and SHOT2-UN (especially compared to the power forward and the point guard).Considering that the differences in most variables are interpreted at the fi rst and second discriminant function, the third discriminant function defi nes the differences in these variables: PF, SHOT1-SU and SHOT1-UN, and primarily between point guards and shooting guards.
Therefore, according to the position of the centroids of the groups of the third function, it can be determined that the players who play the position of the shooting guard are dominant over the point guards in variables PF, SHOT1-SU and SHOT1-UN.Partial dominance in these variables continues respectively according to positions: SMALL FORWARD, POW-ER FORWARD and to a smaller extent to position CENTRE.Point guards are, on the other hand, dominant over shooting guards in variable TO.Mentioned correlations of the fi rst, second and third function are in accordance with the roles and assignments of the fi rst fi ve types of basketball players in offence and defence (Trninić, Dizdar and Jaklinović-Fressl, 1999).

CONCLUSION
Discriminant analysis was carried out in order to determine differences in manifest and latent variables for assessment of situational effi cacy amongst fi ve player positions.Result show that players who play point guard and shooting guard positions are more dominant in variables SHOT3-SU, SHOT3-UN, ASSIST, ST and TO as opposed to centres and power forwards.All gathered results are in consensus with tasks within the roles of players who play positions 1 and 2 (guards).Overall situational effi cacy of players in position 1 is determined by the pressure level in defence, which is evident in the greater number of steals, stopping opponent's transition and stopping dribble penetration.Since they are primarily in charge of ball control, their responsibilities in the game offence are riskiest, so the players in that position have the highest number of turnovers.Furthermore, the acquired results show that the high level of shot abilities is the most important demand to make to the players in position 2. Also important is their level of effi cacy in ball control and passing skills (second by the number of assistances).
The results show that the role of the forward in the organisation of the jump in defence and offence is more important than the role of the point guard or the shooting guard.The forwards are thus dominant in variables SHOT2-SU and SHOT2-UN, especially in relation to the power forward and the guards.The players on position 4 in the phase of defence in situations of switch must also be able to successfully defend the players on the outside positions.For this reason the players in position 4 must have a structure of overall actual quality that satisfi es the criteria for the positions of both forwards and centres in transitional and positional games.Also, the players in position 5 are mostly distinguished from players in other positions by the number of rebounds in defence and offence and the number of blockshots and personal fouls, since their main task is team defence (controlling/protecting the paint and rebounding) and fi ghting for front position for an offensive rebound.
Further on, the centres have most successful shots from the two-point area, and the minimum number of successful and missed three-point shots.Gathered results show that the assistance variable considerably distinguishes guards from forwards and centres, and the shot outside the three-point line distinguishes guards and small forwards from power forwards and centres.Mentioned results are matching for junior and senior Also, the groups of players playing positions 1 and 2 (guards) have a better ratio between assistances and turnovers then forwards and centres.
The differences between the mentioned types of players infl uence the forming of the specifi c process of sports preparation, and directly the evaluation of the specifi cs of players' action and the state of his preparation for executing certain tasks and performing roles in the game.From a pragmatic point of view, keeping track of differences of situational effi cacy of players in diverse game positions enables expert coaches their guidance towards adequate positions in the game.
On the other hand, the parameters of situational effi cacy of elite junior players should be the criterion to weather a certain player meets the effi cacy standards for his position in the game.Also, indicators of situational effi cacy may be the criterion for selecting players within a particular position.It is hereby important to note that player assessment mustn't be based solely on the assessment of situational effi cacy but also on the whole set of an athlete's personality traits.basketball, and show that the three indicators of situational effi cacy differentiate game positions: defence rebounds and blockshots mostly distinguish centres from guards and forwards, and the shot outside the threepoint line distinguish guards from forwards and centres.
Furthermore, in senior basketball, unlike junior, there is a fourth indicator that most of all differentiates the centres from the guards and forwards.This indicator is offensive rebound effi cacy.It is important to mention that from the situational aspect, the high pressure level (on the ball and the pass lines) and timely help in defence form important assumptions of reducing opponent's two and three-point shot effi ciency.This game quality level in defence affects the increase of the probability for defensive rebounding, and thus the overall actual quality, which should necessarily be investigated in the fi eld of functional analysis of the basketball game.It is therefore necessary to explore the effect of interaction between players of one and both teams within the phases of the run of play and the consequence outcomes of the co-opposition actions.
• two-point fi eld goals -successfully (SHOT2-SU)-the number of successful goals within 6.25m line) • two-point fi eld goal -unsuccessfully (SHOT2-UN) -the number of unsuccessful goals within 6.25m line • three-point fi eld goal -successfully (SHOT3-SU) -the number of successful goals beyond 6.25m line)) • three-point fi eld goal -unsuccessfully (SHOT3-UN) -the number of unsuccessful goals beyond 6.25m line • free throw(1,2 and 3) -made (SHOT1-SU) -the number of successful goals behind the free throws line • free throw (1,2 and 3)-missed (SHOT1-UN)the number of unsuccessful goals behind the free throws line • offensive rebound (OR)-the number of ball caught (rebounds off the rim or backboard) on the rebound in the phase of offense • defensive rebound (DR)-the number of ball caught (rebounds off the rim or backboard) on the rebound in the phase of defence • assists (ASSIST) -the number of balls passed to the "open" (undefended) player enabling a successful throw into the basket • personal foul (PF) -the number of fouls; it implies a prohibited, irregular body contact with the opponent, no matter whether the ball is in play or it is a tie ball; fouls regarding the infringement of the rules of conduct (technical fouls) • turnover (TO) -the number of turnovers inthe offense stage as a result of inaccurate assist, bad catch, bad ball dribbling and infringement of the rules (foot faults, intentional kicking of the ball, the ball out-of-bounds, double dribbling, carrying the ball, rule 3,5,8 and 24 seconds and the ball returned into the backcourt) • steals (ST) -The number of steals during the stage of transition or set defence following the team foul during the transition or set offense.Stealing ball during dribbling or cutting off passed balls are some of the ways for defence players to gain possession of the ball • blockshot (BL)-the number of blockshots during the stage of transition or set defence

Table 1
Examinees sample

Table 3
Descriptive statistic parameters of situational effi cacy variables -according to positions (AM -arithmetic mean, SD -standard deviation)

Table 4
Discriminant canonical analysis -manifest variables of situational effi cacy -fi ve player positions