Researchers wanted to know if there is a link between SSRI use and bone density. To conduct the study, researchers compared the bone density of 250 randomly selected SSRI users to the bone density of 250 randomly selected non-SSRI users of the same gender and age. The researchers found that the bone density of SSRI users was 5-10% lower than that of non-SSRI users. Can the researchers conclude that SSRI use decreases bone density? View an Example No, because this is an observational study.