A researcher would like to determine whether an over-the-counter magnesium oil spray has an effect on sleep quality for adults with insomnia . A sample of n = 18 adults is obtained, and each individual is given a standard dose of the spray one hour before bedtime, with sleep quality being measured upon waking in the morning. For the general population of adults , scores on a sleep quality screening test are normally distributed with =60. The adults in the sample had an average score of M = 54 and an s = 8.

Can the researcher conclude that scores on the screening test are significantly different after administering the spray? Use a two-tailed test with = .05. Be sure to state your null hypothesis, a decision about that null hypothesis, and a conclusion explaining your results with an APA format statement. Calculate Cohen's d if necessary.