Question

14) (20) Does the presence of others affect people's willingness to assume responsibility for the welfare of others? For example, does the presence of other people affect our reaction to potentially dangerous smoke seeping from a wall vent? To answer this question, a researcher measured how long (in seconds) it took subjects to ask for help as smoke gradually filled a waiting room. The room was occupied by a subject plus "crowds" of either zero, two, or four experimental confederates (confederates are research assistants who pretend they are subjects) who acted as if they were regular subjects but ignored the smoke. Here are some summary data: zero confederates T = 15 n = 3 SS = 14 two confederates T = 39 n = 3 SS = 14 four confederates T = 54 n = 3 SS = 8 a. (2) What is the independent variable in this experiment, and how many levels does it have? b. (2) What is the dependent variable in this experiment and how is it measured? c. (8) Complete the following summary table. SStotal has already been computed! Source SS df MS F Between Within Total 294 d. (1) State the critical value for the F-ratio. Set a = .05. e. (1) What is your decision about Ho: Reject or retain? f. (6) Tukey's HSD = 6.14. Use this value to draw specific conclusions about this experiment. Please show any work you do.

Answer 1

(a) The independent variable is the presence of others and it has 3 levels.

(b) The dependent variable is people's willingness to assume responsibility for the welfare of others. It is measured on a nominal scale.

(c)

	x	s²	n	n*(x - xgrand)²	(n - 1)*s²
	5	7	3	147	14
	13	7	3	3	14
	18	4	3	108	8
xgrand	12			SSB	SSE
				258	36
Source	SS	df	MS	F	F crit
Between	258	2	129	21.5	5.143
Within	36	6	6
Total	294	8

(d) The critical value is 5.143.