Question

Psychologists in Montreal and Toronto conducted a study to determine if babies show any preference for speech over general noise.1 Fifty infants between the ages of 4-13 months were exposed to both happy-sounding infant speech and a hummed lullaby by the same woman. Interest in each sound was measured by the amount of time the baby looked at the woman while she made noise. The mean difference in looking time was 27.79 more seconds when she was speaking, with a standard deviation of 63.18 seconds. Perform the appropriate test to determine if this is sufficient evidence to conclude that babies prefer actual speaking to humming.

Required:
State the null and alternative hypotheses.

Answer 1

H0 : μ1 - μ2 = 0

H1: : μ1 - μ2 ≠ 0

we reject the Null and we conclude that babies prefer actual speaking to humming.

Explanation:

H0 : μ1 - μ2 = 0

H1: : μ1 - μ2 ≠ 0

Mean difference, d = 27.79

Standard deviation of difference, Sd = 63.18

Sample size, n = 50

The test statistic :

d / (Sd / √n)

Test statistic :

27.79 / (63.18 / √50)

27.79 / 8.9350012

= 3.11

Using the Test statistic score, we can obtain the Pvalue

Using the standard normal table ;

Pvalue = P(x<-Z or x>Z) = 0.0018709

Pvalue is very low

Pvalue < α ; Hence, we reject the Null and we conclude that babies prefer actual speaking to humming.