V - Sherif claimed that, by using several different research methods (observing, tape recording, tests, quantitative as well as qualitative data), he was making his study more valid.
The study has ecological validity, because these were real boys at a real summer camp, doing real activities. Even the specially created tasks (fixing the broken water pipe, pulling the truck) seemed real to the boys. There were some unrealistic features, such as the camp counsellors not intervening until the boys were actually ready to fight each other.
Although this is a field experiment, it lacked a control group. Sherif does not have a 'normal' summer camp to compare his camp to. It may be perfectly normal for food fights and raids to happen in summer camps where the counsellors aren't imposing any discipline. It may be normal for such boys to end up as friends after 3 weeks, regardless of whether they are given special tasks to carry out. In other words, Sherif may have exaggerated how much of the boys' behaviour was due to intergroup factors.
If Michael Billig (1976) is correct, Sherif misunderstood the findings of his own study, because he hadn't realised the experiments made up a third group in the camp, the group with the most power. This casts doubt on the validity of Sherif's conclusions.