## Scavenger versus predator analysis
## January 2017

### Weight analysis

# interaction
Fit Model(
	Y( :weight g ),
	Effects( :treatment, :surface area mm2, :treatment * :surface area mm2 ),
	Personality( "Standard Least Squares" ),
	Emphasis( "Effect Leverage" ),
	Run(
		:weight g << {Lack of Fit( 0 ), Plot Actual by Predicted( 1 ),
		Plot Residual by Predicted( 1 ), Plot Effect Leverage( 1 )}
	)
);
# interaction is not signficant, remove it

# ANCOVA
Fit Model(
	Y( :weight g ),
	Effects( :treatment, :surface area mm2 ),
	Personality( "Standard Least Squares" ),
	Emphasis( "Effect Leverage" ),
	Run(
		:weight g << {Lack of Fit( 0 ), Plot Actual by Predicted( 1 ),
		Plot Residual by Predicted( 1 ), Plot Effect Leverage( 1 )}
	)
);
# surface area is significant, but treatment is not

### Crushing force analysis

# interaction
Fit Model(
	Y( :crushign lbf ),
	Effects( :treatment, :surface area mm2, :treatment * :surface area mm2 ),
	Personality( "Standard Least Squares" ),
	Emphasis( "Effect Leverage" ),
	Run(
		:crushign lbf << {Lack of Fit( 0 ), Plot Actual by Predicted( 1 ),
		Plot Residual by Predicted( 1 ), Plot Effect Leverage( 1 )}
	)
);
# interaction is not significant, remove it

#ANCOVA with linear contrasts
Fit Model(
	Y( :crushign lbf ),
	Effects( :treatment, :surface area mm2 ),
	Personality( "Standard Least Squares" ),
	Emphasis( "Effect Leverage" ),
	Run(
		:crushign lbf << {Lack of Fit( 0 ), Plot Actual by Predicted( 1 ),
		Plot Residual by Predicted( 1 ), Plot Effect Leverage( 1 ), {:treatment <<
		{LSMeans Contrast( [0.5 -1 0.5] ), LSMeans Contrast( [-1 0 1] )}}}
	)
);
# both factors are significant
# predator treatments are significantly stronger than control treatment
# active predator is significantly stronger than scavenger at alpha = 0.1