Question

Most sports injuries are immediate and obvious, like a broken leg. However, some can be more subtle, like the neurological damage that may occur when soccer players repeatedly head a soccer ball. To examine long-term effects of repeated headings, Downs and Abwender (2002) examined two different age groups of soccer players and swimmers. Specifically they examined old and young soccer players and old and young swimmers. They measured their subjects’ performance on a conceptual thinking task to determine if there is any neurological damage in their subjects, a higher score indicates less neurological damage. They found that 20 young soccer players had a M =9; 20 old soccer players had a M = 4, 20 young swimmers had a M = 9, and 20 old swimmers had a M = 8.

a. Draw a table of cell means that includes the actual means for this study. Include marginal means.

b. What factors (independent variable) are used in the prior study? Be sure to include the levels of each factor. What is the dependent measure?

c. List and interpret any main effects.

d. List and interpret any interactions.

Answer 1

(a) The table is:

		Factor B
		Before the First Season	After the First Season	Means
	Contact Sport	9	4	6.5
Factor A	Non-contact Sport	9	8	8.5
	Means	9	6	7.5

(b) There are two factors in this study:

1. Sport - 2 levels

2. Time - 2 levels

(c)

Source	SS	df	MS	F	p-value
Sport	80	1	80	4	0.049073
Time	180	1	180	9	0.003649
Interaction	80	1	80	4	0.049073
Error	1520	76	20
Total	1860	79

There is a main effect of sport. (F (1, 76) = 4, p = 0.049073)

There is a main effect of time. (F (1, 76) = 9, p = 0.003649)

(d) There is an interaction effect. (F (1, 76) = 4, p = 0.049073)