Type and site of melanoma
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 based on a study based on 400 who had been diagnosed with malignant melanoma. For each patient, the site of the tumour and its histological type were recoded.
Site | |||
---|---|---|---|
Type of tumour | Head & neck | Trunk | Extremities |
Hutchinson's | 22 | 2 | 10 |
Superficial spreading | 16 | 54 | 115 |
Nodular | 19 | 33 | 73 |
Indeterminate | 11 | 17 | 28 |
The sample proportions are treated as joint probabilities in the diagram.