51.   There is a bitter rivalry between the two groups.

52.   There has always been strong antipathy between the two groups.

53.   After further clashes in mid-September near Dire Dawa and Harar town, the two organizations sent a joint delegation to attempt to reconcile the various groups.

54.   In recent weeks the two groups had buried their differences to stage joint armed protests across the country.

55.   Reports indicated that the meeting did little to further the prospects of reconciliation between the two groups.

56.   Compare the two average percentage errors obtained by the two groups.

57.   There are a whole set of statistical techniques for assessing the probability that the observed differences between the two groups could have resulted from chance.

58.   In this respect, and prior to the experimental treatment, the two groups are as alike, in all relevant respects, as they can be.

59.   One member of each group was assigned a partner from the other group.