NCSU
ST512
QUIZ 4
Sum2 2011
Q 1. We have the resuls of an experiment conducted to compare two sweet potato cultivars (Hawaii,
NG7570) for drought tolerance1 and two levels of water regimes: control (maintained by regular
watering at or close to field capacity) and Stress (water stressed plants : soil was saturated then allowed
to dry progressively to permanent wilting point). Experimental design: CRD with four repetitions for
each treatment combination. Response is SLA = Specific leaf area (cm2 g-1)
a) Identify the effect. Please fill the blank with one of the following : Main, Interaction, Simple
effect.
o ____________ Mean Difference between Hawaii and NG7570 on average WaterStress
level
o ____________ Mean difference between Hawaii and NG7570 when WaterStress is high
stress compared to the mean difference between Hawaii and NG7570 when WaterStress
is at control level .
o ____________ Differences between WaterStress at high level and control level for
cultivar NG7570
b) The following graph present the means for the four treatment combinations Explain graphically
the interaction effect.
346
350
344
340
Control
340
330
320
310
300
290
value
S
L
A
280
270
260
250
240
Stress
230
220
215
210
Hawaii
NG7570
cultivar
Hawaii
1
treat
Control
Stress
NG7550
Identification of drought tolerant sweet potato (Ipomoea batatas (L.) Lam) cultivars
Prabawardani Saraswati, Mark Johnston, Ross Coventry and Joseph Holtum.
Proceedings of the 4th International Crop Science Congress Brisbane, Australia, 26 Sep – 1 Oct 2004 |
1
July 28, 2011
NCSU
ST512
QUIZ 4
Sum2 2011
c) Calculate
a. the simple effect of WaterStress(A) when cultivar is Hawaii, _________
b. the simple effect of WaterStress (A) when cultivar is N7550. ________
c. How do you interpret their difference? _____________________________________
d) Calculate
a. main effect for WaterStress (A) _____________
b. main effect for Cultivar (B)
_____________
c. interaction effect WaterStress*Cultivar (A*B) ______________
SLA
WaterStress
Control
Cultivar
Hawaii
NG7570
344
346
Mean
345.0
Stress
215
340
277.5
Mean
279.5
343.0
311.25
e) Fill the blanks in the analysis of variance table
Source
DF
Model
3
Sum of Squares
49483.00
Mean Square
F Value
Pr > F
16494.33
10.77
0.001
WaterStress
Cultivar
16129
WaterStress*Cultivar
Error
12
Corrected Total
5
18375.00
1531.25
7858
Use information in table below
a. Calculate the SS for the main effect of WaterStress
b. Calculate the SS for the interaction effect of WaterStress*Cultivar
c. Test the hypothesis of no interaction effect. Use tabular value t(df, 0.05/2) = 2.18 or
F(df1, df2, 0.05) = 4.75.
2
July 28, 2011
NCSU
ST512
Water Stress
Cultivar
Total
QUIZ 4
Control
Control
Hawaii
NG7570
1376
1384
Sum2 2011
Stress
Hawaii
860
Stress
Q
r  cij2
ij
Q2 r  cij2
NG7570
1360
WaterStress
Cultivar
WaterStress*Cultivar
Sum
_______
Q2. A experiment was conducted to study the influence of time of bleeding and diethylstilbestrol (an
estrogenic compound) on plasma phospholipid in lambs. Five lambs were assigned at random to each
of the four treatments groups: treatment combinations are for morning and afternoon times of bleeding
with and without diethylstilbestrol treatment.
a) Identify the design of the study
b) Identify the factors and their levels
c) Write the linear model to be used in the analysis of the data. Indicate the assumption of
the model
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July 28, 2011