The following table shows the aggression scores of 30 laboratory animals reared under three different conditions. One animal from each of 10 litters was randomly assigned to each of the three rearing conditions.

Rearing Condition Litter Extremely Crowded Moderately Crowded Not Crowded 1 30 20 10 2 30 10 20 3 30 20 10 4 25 15 10 5 35 25 20 6 30 20 10 7 20 20 10 8 30 30 10 9 25 25 10 10 30 20 20 Do these data provide sufficient evidence to indicate that level of crowding has an effect on aggression? Let a ¼ :05.