Under what circumstances might you use a 1-sided test of hypothesis rather than a 2-sided test?

In coin flipping the null hypothesis is a sequence of Bernoulli trials with probability 0.5 yielding a random variable X which is 1 for heads and 0 for tails and a common test statistic is the sample mean (of the number of heads) ¯. If testing for whether the coin is biased towards heads a one-tailed test …

In statistics the Mann–Whitney U test (also called the Mann–Whitney–Wilcoxon (MWW) Wilcoxon rank-sum test or Wilcoxon–Mann–Whitney test ) is a nonparametric test of the null hypothesis that for randomly selected values X and Y from two populations the probability of X being greater than Y is equal to the probability of Y being greater than X.. A similar nonparametric test used on ...

Sign test - Wikipedia

Sign test - Wikipedia

Welch's t-test - Wikipedia

Sign test - Wikipedia

In Dunnett's test we can use a common table of critical values but more flexible options are nowadays readily available in many statistics packages such as R. The critical values for any given percentage point depend on: whether a one- or- two-tailed test is performed; the number of groups being compared; the overall number of trials.

In statistics the Wald test (named after Abraham Wald) assesses constraints on statistical parameters based on the weighted distance between the unrestricted estimate and its hypothesized value under the null hypothesis where the weight is the precision of the estimate. Intuiti...