A classic experiment by Dutton & Aron (1974) examined men\'s attraction to a fem

Question

A classic experiment by Dutton & Aron (1974) examined men's attraction to a female they met in either one of two conditions: on a high unstable, shaky bridge or on a low sturdy bridge. Later, they rated the attractiveness of the woman. The following data is a generated replica of this study. Attractiveness was rated as 1-10 with 10 being very attractive. The researchers want to evaluate how the independent variable (bridge height) affects attractiveness ratings. More specifically, they predict that those men in the higher bridge condition will rate the woman as being more attractive. a.) State your null and alternative hypotheses. b) What are your degrees of freedom and critical value(s) given an alpha = .05 level? f) What is the estimated effect size in this study in terms of Cohen's d? Do you characterize it as being small, medium or large? g.) Calculate 99% confidence interval.

Explanation / Answer

here we use t-test for testing of difference of two sample means and

t=(mean1-mean2)/((sp*(1/n1 +1/n2)1/2) and sp2=((n1-1)s12+(n2-1)s22)/n and with df is n=n1+n2-2

(a) null hypothesis H0: high bridge=low bridge

alternate hypoghesis H1: high bridge > low bridge

(b) degree of freedom=df=17+22-2=37 and

critical value=t(0.05,37)=2.03

(c) pooled variance= sp2=((n1-1)s12+(n2-1)s22)/n=(201+154)/(17+22-2)=9.595 and n=n1+n2-2

pooled standard deviation=s=sqrt(9.595)=3.0976

Cohen's d effict size=(M1-M2)/s=(6.82-4.57)/3.0976=0.7264

it may be characterize as large

(d) SE(difference)=s*sqrt(1/n1+1/n2)=3.0976*sqrt(1/17 + 1/22)=1   

(1-alpha)*100% confidence interval for difference =difference ±t(alpha/2,n)*SE(difference)

99% confidence interval =(6.82-4.57)±t(0.1/2,37 )*1=2.25±2.72=(-0.47,4.97)

following calculation has been generated

s=sqrt(SS/(n-1))

high bridge low bridge n 17 22.00 SS 201 154.00 M 6.82 4.57 sample sd=s 3.54436172 2.708012802

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