Unlike all other types of research designs, a true experiment has both ________ and _________ .

To discover how many people wash their hands after using the toilet, you decide to go into a public toilet at UNSW and hide in a stall so you can count how many people wash their hands before they leave. What kind of measurement method are you using?

Evie has recently conducted a study where she found that the number of crimes has increased in areas where new apartment blocks have been built. She concludes that as apartment numbers increase so do incidences of crime. Her colleague points out that the number of people have also increased and that this may be causing an increase in both levels of crime and the number of apartment blocks being built.

What type of correlational relationship is this?