One of assumptions we sometimes need to make when performing statistical inferences is that the response variable in population has a Normal distribution. Is it possible to check that this assumption is satisfied?
A. Yes - we can be absolutely sure population was Normal if a plot of the data looks perfectly bell-shaped and symmetric.
B. Yes - we can be absolutely sure population was Normal if a plot of the data looks roughly bell-shaped and symmetric.
C. Yes - we can be absolutely sure population was Normal if a plot of the data has no major outliers.
D. No - we can't really check this assumption since all data will look perfectly bell-shaped as well as symmetric, even if the population was not Normal.
E. No - we can't really check this assumption since we don't have whole population, but the t distribution is robust to modest departures from Normality, so we can employ it if a plot of data has no major outliers.