Question

3. (2.5 points) To determine the effect of two glass types and three phosphor types on the light output of a television tube, light output is measured by the current required in series with the tube to produce 30 foot-lamberts of light output. Thus the higher the current is in microamperes, the poorer the tube is in light output. Three observations were taken under each of the six treatment conditions and the experiment was completely randomized. The following data were recorded. Glass Phosphor Type Type 280 300 270 290 310 285 285 295 290 230 260220 235 240 225 230 240 235 Analyze the data and draw conclusions. Use a 0.05. a. b. Prepare appropriate residual plots and comment on the model's adequacy. What is the optimal Glass type and Phosphor type? c.

Answer 1

data

	A	B	C
1	280	300	270
	290	310	285
	285	295	290
2	230	260	220
	235	240	225
	24	235	230

a)

we use ANOVA two way

Anova: Two-Factor With Replication
SUMMARY	A	B	C	Total
1
Count	3	3	3	9
Sum	855	905	845	2605
Average	285	301.66667	281.66667	289.44444
Variance	25	58.333333	108.33333	134.02778
2
Count	3	3	3	9
Sum	489	735	675	1899
Average	163	245	225	211
Variance	14497	175	25	5045.25
Total
Count	6	6	6
Sum	1344	1640	1520
Average	224	273.33333	253.33333
Variance	10274	1056.6667	1016.6667
ANOVA
Source of Variation	SS	df	MS	F	P-value	F crit
Sample	27690.88889	1	27690.889	11.159181	0.005882	4.747225
Columns	7388.444444	2	3694.2222	1.4887386	0.264518	3.885294
Interaction	4268.444444	2	2134.2222	0.8600725	0.447647	3.885294
Within	29777.33333	12	2481.4444
Total	69125.11111	17

p-value of Glass Type is 0.006 < alpha

hence Glass Type is significant

however Phosphor Type and interaction are not significant

c)

Glass type 1 and Phosphor type B