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Characterize variables
 Most of the question is to study the effects of factor(s) X on factor(s) Y
 Example 1: whether goldfinches have a color preference in feeders? > to study the effect of feeder color(X) on goldfinches' frequency and duration of feeding (Y)?
 Example 2: how E.coli strain O157:H7 is affected by antibiotics? > to study the effect of antibiotic (X) on the bacterial growth (Y)?
 Example 3: how different wheat cultivars respond to the attact of Cereal Cyst Nematodes? > to study the effect of the cultivar, chemical treatment and plot size (X) on wheat plant height and multiplication factor/growth rate (Y)
 Next, identify the types (what are they?)of the X (independent) variable(s) and Y (dependent) variable(s)
 Example 1

Dependent Variable(Y) 
Independent Variable(X) 
Symbol 
Y1 
Y2 
X 
Name 
Goldfinches'feeding frequence 
Goldfinches's feeding time 
Feeder's color 
Type 
ordinal 
ratio 
norminal 

Dependent Variable(Y) 
Independent Variable(X) 
Symbol 
Y 
X 
Name 
Bacterial growth 
Antibiotic type 
Type 
norminal 
norminal 
 Once the variables are identified, we are ready to select methods.

Dependent Variable(Y) 
Independent Variable(X) 
Symbol 
Y1 
Y2 
X1 
X2 
X3 
Name 
Plant height 
Multiplication 
Cultivar 
Chem.treatment 
Plot size 
Type 
ratio 
ratio 
ordinal 
norminal 
ratio 
