Researchers investigated the effect of a brief training program on the ability of health care professionals to detect deception. In part of the study, 26 health care workers were shown videos in which individuals sometimes showed a genuine smile, and sometimes showed a fake smile. Individuals completed this task before and after completing a 3 hour session designed to help them recognize deception. The participants' responses were evaluated and they were given a discrimination accuracy score (high positive scores indicate a person is correctly discriminating between a genuine smile and a fake smile, values near 0 indicate the individual is not discriminating between a genuine smile and a fake smile, and negative values indicate that the individual is misclassifying genuine smiles as fake and fake smiles as genuine). The results of the study are given as:
Difference (d=After - Before): mean (d) = 0.618, sd(d) = 1.412
The researchers were interested in testing whether the training program had an effect different than zero. The symbol: μd represents the population mean for the difference.
One Sample t-test
data: expressions
t = 2.2317, df = ?, p-value = ?
alternative hypothesis: true mean is not equal to 0
95 percent confidence interval:
0.04768086 1.18831914
sample estimates:
mean of x
0.618
- H(o):
- H(a):
- degrees of freedom for the t-test:
- Observed t-Test statistic:
- P-value:
- Decision (choose one): (Reject H(o), Do not reject H(o)):
- Conclusion (choose one): There (is, is not) suffecient evidence to suggest that the population means differ.
A. is not
B. 0.7589
C. Reject H(o)
D. 1.96
E. μd≠ 0
F. μd < 0
G. 25
H. is
I. μd= 0
J. Do not reject H(o)