Q#13 An acceptable rationale to perform a one-tailed (one-sided) test for statistical significance is: A-

Q#13 An acceptable rationale to perform a one-tailed (one-sided) test for statistical significance is:
A- The one-tailed hypothesis test is proposed during study design, and well justified.
B- There are inadequate funds or resources to study large enough to be powered for 2-tailed testing.
C- A need to examine multiple secondary hypotheses.
D- During the study design phase, examination of sub-strata was proposed.
E- The study’s Data Safety Monitoring Board demands this analytic approach.
Q#14 Concerning the COVID-19 pandemic, which of the following is correct? (Give the BEST answer)
A- Surgical masks provide better or equal protection than an N95 mask.
B- A distance of 3 feet or less from an infected person provides a high degree of protection from acquisition of infection.
C- Droplet nuclei can remain suspended for an extended period of time.
D- A and B
E- B and C
Q#15 Regarding a paired t-test, which is the BEST (most true) statement?
A- It usually gives the same result as performing an unpaired t-test on the same data.
B- Controls are matched to cases.
C- It is useful when comparing numeric pre- and post-intervention assessment on a set of subjects.
D- It requires data to be consistent with the “binomial” distribution.
E- Logarithmic transformation usually invalidates the statistic.
Q#16 You have a cohort of older subjects who were all immunized for SARS-CoV-2 using either the Moderna or Pfizer vaccines, but their status with respect to actually having been infected with the virus is not clear. Which of the following would suggest that the individual had a history of COVID-19 infection?
A- The presence of IgG in the serum that is specific for the Spike protein
B- The presence of IgA in the nasal secretion that is specific for Spike protein
C- The ability of the NK cells from the patient to kill target cells infected with SARS-CoV-2
D- The presence of memory T cells that are specific for SARS-CoV-2 nucleocapsid peptides
E- The ability of neutrophils from the patient to make extracellular NETs