The situation in which an apparent correlation between two variables is in fact explained by a third variable that correlates with one or both of the variables under investigation. If confounding is not recognized, it can lead to the false assumption that two variables are directly related (a spurious correlation). For example, research might show an apparent association between the growth in insect populations in a certain area and a decline in various plant species: however, both observations might well be accounted for by a rise in temperature (the confounding or hidden variable).