Support and grief state after neonatal death

Use this page to show that the marginal probabilities are sums of joint probabilities, such as

Click the formulae for the marginal probabilities to stack the bars.

(The values are actually sample proportions rather than probabilities but the diagram illustrates the concept.)

The diagram is based on a real data set which describes the state of grief of 66 mothers who had suffered a neonatal death and the amount of support given to them.

  Support
Grief state Good Adequate Poor
I 17 9 8
II 6 5 1
III 3 5 4
IV 1 2 5

The sample proportions are treated as joint probabilities in the diagram.