# Graph description: Figure 18. Interaction between abdominal and arm circumference in their effects on BMI

This is a scatter diagram.

The horizontal axis shows abdominal circumference in centimetres and is numbered 40, 60, 80, 100, 120. The vertical axis shows body mass index in kilogrammes per square metre and is numbered 10, 20, 30, and 40.

There is a fairly strong relationship between body mass index and abdominal circumference. The cloud of points lies between body mass index = 10 and 20 when abdominal circumference = 50, to between body mass index = 30 and 40 when abdominal circumference = 110.

There are two types of points, shown by closed and open symbols. The closed symbols indicate mid upper arm circumference less than the median, the open symbols indicate mid upper arm circumference greater than or equal to the median. The closed symbols are all in the lower half of abdominal circumference, to the left of abdominal circumference = 85. The open symbols are mostly in the upperer half of abdominal circumference, and are all to the right of abdominal circumference = 60. There is overlap between abdominal circumference = 60 and 85.

There are two straight lines on the graph. Corresponding to the closed symbols is a line from abdominal circumference = 40, body mass index = 15 to abdominal circumference = 120, body mass index = 25. Corresponding to the open symbols is a line from abdominal circumference = 40, body mass index = 13 to abdominal circumference = 120, body mass index = 32. Hence the line for mid upper arm circumference greater than or equal to the median is steeper than the line for mid upper arm circumference less than or equal to the median.

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