Question

A study found a high positive correlation (r = .921) between the size of the hospital where a patient's surgery was performed and the length of the patient's stay following surgery. (x = number of beds in the hospital, y = number of days following surgery before release from the hospital). Is the most reasonable explanation for this correlation cause-and-effect or a hidden cause? If it is not cause-and-effect, suggest a more reasonable hidden cause.

Answer 1

Correlation doesn't imply causation. But the Converse is not true.

Here the x (no of bed in a hospital) has no cause and effect relationship with y ( no of days following surgery before release from the hospital) . Because value of x does not affect value of y. But there is a third agent which is affecting both.

Maybe the third agent is severeness of disease , it is generally seen that the patient suffering from severe disease goes to bigger hospital and since the disease is severe the patient has to stay for long to get completely cured or trrated. One reason is this.

There may be another reasons also. But the key idea s that for cause and effect relationship we have to come up with scientific evidence. Which supports the change in one variable due to other. It has nothing to do with statistical measures. Apart we do depict cause and effect relationship in the statistical study of design of experiment but that is also based on the low of nature.