A microbiologist is studying the effects of a particular treatment on culture specimens in a lab. The experiment is such that measurements are taken on the culture prior to the treatment and again 2 weeks after the treatment has been administered. The treatment and cultures are quite expensive so the biologist only has 6 cultures. In addition to the small sample size, the biologist expected there to be great fluctuations in the response of the cultures (outliers or non-normality). She would like to know if the treatment shows any change. Which test could she use