Question

2. Earlier in this chapter, we discussed that iron supplements are popular in part because they raise oxygen levels in our bodies, and increased oxygen levels help us feel more energetic. We also said that consuming an iron supplement with a drink high in Vitamin C enhances the effects of the iron supplement. A researcher has a sample of 40 people randomly assigned to two factors: iron supplement and Vitamin C consumption. Specifically, people were randomly assigned either to take an iron supplement or not to take an iron supplement. In addition, people were also randomly assigned either to consume a glass of orange juice (which is high in Vitamin C) or not to consume a glass of orange juice. The researcher uses a pulse oximetry to measure oxygen levels as the dependent variable (to keep the calculations simple, we are using intentionally hypothetical numbers for oxygen levels).The data is presented below. Carry out the analysis of variance using SPSS and determine whether there are any main effects or an interaction. Make a line graph of the results and interpret the pattern of the results.

	Iron Supplement
	Took Supplement	Did not take Supplement
Ingested Vitamin C	9	1
	7	3
	8	3
	8	3
	9	2
	8	3
	9	3
	7	2
	6	2
	8	1
Did Not Ingest Vitamin C	4	3
	5	2
	5	4
	6	2
	6	2
	7	2
	6	2
	5	3
	5	4
	4	2

Answer 1

Answer:

2. Earlier in this chapter, we discussed that iron supplements are popular in part because they raise oxygen levels in our bodies, and increased oxygen levels help us feel more energetic. We also said that consuming an iron supplement with a drink high in Vitamin C enhances the effects of the iron supplement. A researcher has a sample of 40 people randomly assigned to two factors: iron supplement and Vitamin C consumption. Specifically, people were randomly assigned either to take an iron supplement or not to take an iron supplement. In addition, people were also randomly assigned either to consume a glass of orange juice (which is high in Vitamin C) or not to consume a glass of orange juice. The researcher uses a pulse oximetry to measure oxygen levels as the dependent variable (to keep the calculations simple, we are using intentionally hypothetical numbers for oxygen levels).The data is presented below. Carry out the analysis of variance using SPSS and determine whether there are any main effects or an interaction. Make a line graph of the results and interpret the pattern of the results.

SPSS used

SPSS command:

UNIANOVA oxygen BY Iron C
/METHOD=SSTYPE(3)
/INTERCEPT=INCLUDE
/PLOT=PROFILE(Iron*C) TYPE=LINE ERRORBAR=NO MEANREFERENCE=NO YAXIS=AUTO
/PRINT DESCRIPTIVE
/CRITERIA=ALPHA(.05)
/DESIGN=Iron C C*Iron.

Descriptive Statistics
Dependent Variable:   oxygen
Iron	C	Mean	Std. Deviation	N
no	no	2.6000	.84327	10
	yes	2.3000	.82327	10
	Total	2.4500	.82558	20
yes	no	5.3000	.94868	10
	yes	7.9000	.99443	10
	Total	6.6000	1.63514	20
Total	no	3.9500	1.63755	20
	yes	5.1000	3.00701	20
	Total	4.5250	2.45981	40

Tests of Between-Subjects Effects
Dependent Variable:   oxygen
Source	Type III Sum of Squares	df	Mean Square	F	Sig.
Corrected Model	206.475a	3	68.825	83.990	.000
Intercept	819.025	1	819.025	999.488	.000
Iron	172.225	1	172.225	210.173	.000
C	13.225	1	13.225	16.139	.000
Iron * C	21.025	1	21.025	25.658	.000
Error	29.500	36	.819
Total	1055.000	40
Corrected Total	235.975	39
a. R Squared = .875 (Adjusted R Squared = .865)

The main effect Iron is significant, F= 210.173, P<0.001.

The main effect C is significant, F= 16.139, P<0.001.

The interaction effect is significant, F= 25.658, P<0.001.

The line plot shows the interaction is significant.