Question

Use SPSS for this Application Exercise:
A developmental psychologist suspects that first-born children tend to develop language skills faster than their younger siblings. An explanation for the phenomenon is that first-borns have undivided attention from their parents. As such, it is reasonable that twins and triplets have slower language development than single children. The psychologist collects measures of language skills for each child at age 3 in participating families. The data are below. What can the psychologist conclude with an α of 0.05?

single	twins	triplets
9 8 7 10 9 7 6 7 9 7 6 10	6 4 8 5 8 6 2 8 7 8 4 8	5 7 4 11 4 5 2 4 6 4 8 4

a) What is the appropriate test statistic?
---Select--- na one-way ANOVA within-subjects ANOVA two-way ANOVA

b) Input the appropriate value(s) to make a decision about H₀.
p-value = ______________________ ; Decision:  ---Select--- Reject H0 Fail to reject H0

c) Using the SPSS results, compute the corresponding effect size(s) and indicate magnitude(s).
η² = ______________________________ ;  ---Select--- na trivial effect small effect medium effect large effect

d) Make an interpretation based on the results.

1) At least one family type (i.e., single, twins, or triplets) is different on language skills.

2) None of the family types (i.e., single, twins, or triplets) differed on language skills.  

Answer 1

Sol:

Here we want to test the

Null hypothesis

H0 : A = B = placebo

alternate hypothesis

Ha: atleast one A is different from others

(a)

One Way ANOVA,

(b)

Reject H0

since the p-value(Sig.) =0.01 is less than alpha the level of significance=alpha=0.05

ANOVA

Source	sum of squares	df	Mean Square	F	p-value .
between groups	36.5	2	18.25	4.916	0.01357
within groups	122.5	33	3.7121
Total	159	35

(c)  

0.5266 is Medium

proportion of variance in Y explained by X

Cohen’s (1988) guidelines or eta square is

• Small: 0.01
• Medium: 0.059
• Large: 0.138

d).

since p-value=0.01 is less than alpha=0.05,

so

we reject the null hypothesis and conclude that at least one of the formulation is different from others , so right choice would be first AT LEAST ONE OF THE FORMULATION DIFFER ON PAIN.

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