To more directly examine the progress of the disease the researchers took biopsies every 60 days after infection for 600 days for each individual, counting levels of the BSE prion in the nervous tissue (10 measurements for each of the 42 mice, making 420 measurements in total).

What are the number of true independent replicates in this study?

A. The 42 mice

B. The 10 biopsies per mouse

C. The 420 measurements in total

Two different research groups, one in america and one in the UK wished to examine incubation times for BSE in two different genotypes. The american group tests genotype A and the Uk group tests genotype B. The find that genotype A has a longer incubation time than genotype B and conclude that again there is signfiicant differenct in incubation timese between the two genotypes.

A. This study is confounded by the use of hierarchial sampling by testing all of genotype A in the USA and genotype B in the UK.

B. This study is confounded spatially by testing all of genotype A in the USA and all of genotype B in the UK.

C. This study is confounded by only testing two genotypes.