Question

A researcher measures the relationship between the number of interruptions during a class and time spent "on task" (in minutes). Answer the following questions based on the results provided.

Number of Interruptions - 9, 4, 6,3

Time Spent "On Task"- 18, 38, 17, 32

Part (a) Compute the Pearson correlation coefficient. (Round your answer to three decimal places.)

Part (b) Multiply each measurement of interruptions times 3 and recalculate the correlation coefficient. (Round your answer to three decimal places.)

Part (c) Divide each measurement in half for time spent "on task" and recalculate the correlation coefficient. (Round your answer to three decimal places.

Answer 1

Part (a)

Pearson correlation coefficient : r

x: Number of Interruptions

y: Time Spent "On Task"

	x	y	xy	x2	y2
	9	18	162	81	324
	4	38	152	16	1444
	6	17	102	36	289
	3	32	96	9	1024
Total	=22	=105	=512	=142	=3081

Pearson correlation coefficient : r = -0.793

Part (b) Multiply each measurement of interruptions times 3 and recalculate the correlation coefficient. (Round your answer to three decimal places.)

	x	y	xy	x2	y2
	9*3=27	18	486	729	324
	4*3=12	38	456	144	1444
	6*3=18	17	306	324	289
	3*3=9	32	288	81	1024
Total	=66	=105	=1536	=1278	=3081

Pearson correlation coefficient : r = -0.793

Part (c) Divide each measurement in half for time spent "on task" and recalculate the correlation coefficient. (Round your answer to three decimal places.

	x	y	xy	x2	y2
	9	18/2=9	81	81	81
	4	38/2=19	76	16	361
	6	17/2=8.5	51	36	72.25
	3	32/2=16	48	9	256
Total	=22	=52.5	=256	=142	=770.25

Pearson correlation coefficient : r = -0.793