The effect of computerised analysis as feedback on the performance of elite squash players

Murray S, Maylor D & Hughes M:
Centre for Notational Analysis, University of Wales Institute Cardiff.

Published in Lees A, Maynard I, Hughes M & Reilly T(Eds),Science and Racquet Sports II. E & FN Spon: London, pp. 235 – 246. 1998

1 Introduction:
Feedback can be broken into two basic forms, qualitative and quantitative, both these playing an equally important role. Recent research, however, has shown that more objective, i.e. quantitative, the feedback the greater effect it has on performance (Smoll, 1972; Reeve and Magill, 1981; Franks, Goodman, and Millar, 1983; Magill and Wood, 1986; Magill, 1993, and Franks, 1997a).

Many studies have been done on the patterns of play and rally ending outcome of the game of squash (Hughes, 1985 and 1986; Knight and Hughes, 1995; Franks, 1997b). Surprisingly, however, the study of feedback and the psychological aspects of the game has received little attention and still appears to be a ‘grey’ area in the sport of squash.

Brown and Hughes (1995) studied the differing effects that qualitative and quantitative feedback had on the performance of junior squash players. The study found no change in the overall group performance (p<0.01) and only one of the individual subjects showed a slight improvement (p<0.05). Their study design was limited by the fact that that they used adolescent players and the results were compromised by the effects of maturation.

The aim of this study was to establish the effect that detailed quantitative feedback had on the performance of elite and sub-elite standard squash players. By providing accurate and detailed feedback from a computerised squash analysis system and observing matches after the feedback provision it was possible to gauge any temporal transition in the performers patterns of play and winner/errors distributions. The subjects also completed Sports Psychological Skills Questionnaires (S.P.S.Q.) to make it possible to evaluate changing psychological states over the feedback provision period.

It was hypothesised that the players would produce a significant increase in total winners played and a decrease in total errors played. It was also hypothesised that differing psychological states would have a direct impact upon performance levels.

2 Methods:

2.1 Subjects:
Two different standard groups of players were selected. An elite group (N=4), all of which were ranked in the top 10 senior in Wales, and a sub-elite group (N=4), all ranked between 10-30 senior in Wales.

2.2 Apparatus and Data processing:
The software used to input data was designed by Hughes (1995) and was validated by Brown and Hughes (1995, see Science and racquet Sports, pp. 232-237). The display on the computer split the court into sixteen cells allowing a positional entry of the rally ending shot, type of shot played, a winner or error decision, identification of player, and no. Of shots in the rally. Winners and Errors were used as an index of performance.

2.3 Procedure:
The subjects’ play was recorded during a series of competitive matches (N=4) at the start of the study (T1). These matches formed the basis of the initial feedback. Over the next eight weeks , matchplay for each of the players was video-taped and computerised analysis and video feedback provided, combined with specific on court practices and training (designed around findings of T1). Finally, a second series of competitive matches (N=4) were recorded and analysed (T2). By comparing the results of T1 and T2 differences in performance could be recorded. Training diaries were kept and psychological (S.P.S.Q.) questionnaires were administered at the beginning of T1 and T2. A Chi-square statistical test was implemented between the results of T1 and T2 to test for significant changes.

3 Results and Discussion:
Table 1. Chi-square X values representing changes in specific shots between T1 and T2 for elite and sub-elite performers

It is evident from the above results that the sub-elite performers showed a greater improvement in the specific shot types. The most significant changes were decreases in sub-elite errors drives, drops, and boasts (p<0.05). Arguably, although the elite performers only displayed a slight increase in performance, this would still have largely effected performance due to the fact that the slightest change in performance at an elite level invariably changes the outcome of a match (Thomas and Thomas, 1994).

Fig. 1. Elite change in performance between T1 and T2.
Note: Figures in bracquets refer to absolute number of shots played

Fig. 2. Sub-elite change in performance between T1 and T2
Note: Figures in bracquets refer to absolute number of shots played

Figures 1 and 2 show the subjects change in winners and errors over the feedback provision period. It is clear that the sub-elite performers were subject to a far greater change than the elite. Elite subjects 1 and 2 displayed a marginal increase in winners, however these results were not deemed substantially significant (p<0.05). Elite subject 4 showed an emphatic increase in winners (p<0.01) representing his more positive approach to the game in T2. Sub-elite performers A,C and D all showed significant (p<0.05) increases in winners, with subject B showing a slight decrease, although not substantially significant (p<0.05). The elite subjects showed mixed results with regards errors (see Fig. 1). Subject 1 and 2 displayed a slight decrease in errors, where subject 3 and 4 a slight increase, non of these results were found to be significant. The sub-elite performers (see Fig. 2) all displayed a significant decrease (p<0.05) in the number of errors played between T1 and T2.

Fig.3. Elite and Sub-elite differences between T1 and T2

It is evident from Fig. 3 that the sub-elite group as a whole reacted more positively to provision of the feedback. The sub-elite performers displayed a significant increase in winners (p<0.05) and a significant decrease in errors (p<0.05). However, although the elite performers displayed the same trends, the results found were not deemed substantially significant (p<0.05), however, still had effect upon performance. It is often argued that in certain cases a 95% level of confidence is too stringent for useful analysis of a group that is only likely to display marginal change (Kazmier, 1988). Arguably, the use of stringent confidence levels or indeed statistics on elite groups showing only minimal changes may need to be reviewed.

Table 2. S.P.S.Q. results for elite performers

The sub-elite performers showed no change in psychological states between T1 and T2. However, due to intra personal nature of group of elite performers the performance of any given subject could have a direct effect upon another member of the group. It appears that this certainly occurred in this study. Subjects 1 and 2 were best the results throughout the study period, invariably at the cost of the subject 3. This clearly effected the playing patterns of subjects 3, and it may argued that it also effected his psychological state (see Table 2). Having received the initial feedback at the end of T1 subject 4 initiated himself on a psychological skills training programme, and although there is little evident showing this effected his matchplay, it clearly put him in better state of mind in T2 (see Table 2).

Table 3. Elite and Sub-elite mean hours training per week

The elite players spent considerably more time training than the sub-elite. This reflects their dedication and motivation towards the game. Interestingly, elite subject 1 spent the most hours training, had the best outcome results, and most solid psychological state. Where as elite subjects 3 and 4 trained the least, showed the most unstable state of mind over the study period and produce the worst performances. Arguably there is correlation between the above mentioned influences acting upon the subjects of the elite group. However, sub-elite subject A and C spent the least amount of time training, nevertheless, they were the subjects who showed the greatest improvement in performance.

4 Conclusions:
It appears that both groups in this study reacted positively to the feedback provided. The sub-elite group showed a greater change in performance but, as argued before, the minimal elite change had as great an effect on match results. However, in order to gauge the exact effect of feedback alone, complete control conditions would be needed in order to minimise the effect of other external variables. The sub-elite performers displayed more significant improvements (p<0.05) in specific shot types. Arguably, this is representative of the relatively easy task of improving performance when at a lower level of competence (Thomas and Thomas, 1994). It is clear that the intra personal nature of the elite group had a impact on the study. This may need to be noted by coaches working with such groups in the future. In this study the psychological states of the subjects also had effect on their performance, be it positive or negative, E, and evidently further research into this area would improve the status and understanding of the competitive squash coach. In this study quantitative feedback induced a significant temporal transition in performance levels of both groups. The findings were consistent with earlier research on the effect of quantitative feedback (Schmidt, 1982; Salmoni, Schmidt, and Walter, 1984; Magill, 1993; Franks, 1997a).

5 References:

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