Wednesday, 28 November 2007

Don't jump! Advice for goalkeepers from economic psychology

You have to feel sorry for goalkeepers. While strikers take all the glory for scoring goals, keepers only tend to get noticed when they make mistakes. Well now a little bit of goalkeeping help is at hand from an unlikely source: economic psychology.

Ofer Azar and colleagues in Israel watched hours of archival footage and noticed that goalkeepers save substantially more penalty kicks when they stay in the centre of goal than when they jump to the left or right. Yet paradoxically, in 93.7 per cent of penalty situations, keepers chose to jump rather than stay in the centre.

In fact, analysis of 286 penalty kicks taken in elite matches around the world showed that keepers saved 33.3 per cent of penalties when they stayed in the centre, compared with just 12.6 per cent of kicks when they jumped right and 14.2 per cent when they jumped left.

The researchers believe the anomaly may be a reversed manifestation of what is known in economic psychology as the inaction effect or the omission bias. That is, people tend to suffer more regret after a negative outcome follows something they've done, compared with something they haven't done. In the case of keepers, the researchers surmised, they feel greater regret at letting a goal in after standing still in the centre, compared with jumping. If the ball ends up in the back of the net after they've jumped, at least it will have felt as though they had made a decent attempt to save it.

This account appeared to be supported by a survey of 32 top Israeli keepers. Of the 15 who said their goal position would make any difference to how bad they felt about letting in a penalty, 11 said they would feel worse if they just stayed in the centre.

Of course, if goalkeepers around the world heed the lessons from this study and start staying in the centre of goal more often, presumably there will only be a brief period before penalty takers notice and start aiming more for the sides of the goal, thus balancing things out again. So give keepers a headstart - forward them this study, but don't tell any strikers about it!
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Bar-Eli, M., Azar, O.H., Ritov, I. & Keidar-Levin, Y. (2007). Action bias among elite soccer goalkeepers: The case of penalty kicks. Journal of Economic Psychology, 28, 606-621.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

9 comments:

  1. Anonymous5:01 pm

    This article is retarded.

    "97.7 per cent of penalty situations, keepers choose to jump rather than stay in the centre."

    "In fact, analysis of 286 penalty kicks taken in elite matches around the world showed that keepers saved 33.3 per cent of penalties"

    That means exactly 6 (six!) people did not jump. That means exactly 2 idiot keepers who did not jump got lucky and saved a goal. That means that if exactly 1 of those 2 had happened to score by a hair, then the percentages (16% v. 13%) would be statistically identicaly.

    The sample of people not jumping is ridiculously small.

    How about you just run an experiment instead of data mining falsehoods.

    j

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  2. Please note the correction to the report. I should have written 93.7 per cent, not 97.7 per cent, regarding how often keepers chose to stay in the centre. My apologies for the error. That means there were 18 occasions when keepers chose to stay in the centre.

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  3. The study still suffers from a major statistical flaw. The error bar on that datum is 1/sqrt(18) = +/-23.5%, meaning that one cannot reliably say that it is better to do that than to jump--i.e., one expects the keepers to actually save those shots between 9.8 and 56.8 percent of the time. Thus, one cannot reject the null hypothesis that staying is better than jumping. In addition, it is likely that (if in fact keepers save more by staying in the centre) the only reason they do so is that it is unexpected; if any significant number of keepers heed this advice, that number will drop precipitously.

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  4. Anonymous1:29 pm

    haha

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  5. Anonymous4:10 pm

    Plus... the keepers that stayed in the center may have done so because they suspected that was where the shooter was going either from prior match recon or footwork by the person taking the PK. It doesn't translate to plant your feet in the center, hold your ground and you will save 1/3 of your penalty kicks.

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  6. Anonymous8:01 am

    How is possibly supposed to be good advice considering the vast majority of penalty takers aim for the sides?

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  7. Stats show 88% of penalties saved in football history were when keepers wore green shirts....

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  8. Both Azar and Bar-Eli, the authors of several reports on the topic of decision making and penalty saves in soccer fail 100% of the time to note any influence of anticipatory cues and deception from the penalty takers. Check the penalty by Pirlo vs Joe Hart at Euro 2012 if you want to understand this. Naive research at best.

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  9. Maybe they should take out of the analysis all the "well-taken" penalties? That is, if it's hit with power into the side netting, you're probably not going to save it even if you did choose right, unless you start moving early and the shooter doesn't see that and shoot the other way.

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