21.   A department, in which women were employed wiring the back plane of telephone exchanges, had been divided into a test group and a control group.

22.   In this case a control group would be selected which matches as closely as possible, member for member, the characteristics of the people constituting the experimental group.

23.   The presumed causal factor, normally referred to as the independent variable, is withheld from the control group and administered only to the experimental group.

24.   Of course, one major problem is ensuring that the experimental and the control groups are as alike as possible in all relevant respects.

25.   This was true for patients as well as the control group.

26.   The healthy control group received no additional treatment.

27.   The Figure shows the systemic endotoxin concentrations plotted against colon macroscopic score for the disease control group and the combined terra fullonica groups.

28.   The enteral administration of kaolin and terra fullonica produced a significant reduction in systemic endotoxaemia compared with the disease control group in this experimental model of colitis.

29.   No improvement in weight gain, serum albumin, lactate or alkaline phosphatase concentrations was demonstrated in the treatment groups compared with the disease control group.

30.   The control group comprised patients with non-specific abdominal symptoms other than constipation.