Is narcissism a more common personality trait today than it was a few decades ago?  It is known that the mean population score on the Narcissistic Personality Inventory (NPI) for students attending University of South Alabama around 20 years ago was μ= 15 (Twenge, 2010).  Interested in the narcissism levels of students in the year 2020, a researcher administers the NPI to a random sample of 25 University of Alabama sophomores this Spring term. The mean NPI score from the researcher’s sample of sophomores is M = 16.5, with s = 3.4. 1. Find the obtained (i.e., computed) test statistic for a sample (n=25) with a mean of 16.5   2. Make a statistical decision about the null. Will you reject or fail to reject the null based on your sample data?    3. Justify your decision about the null.

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