Table 1

Stepwise multiple regression models: brain components

Brain components (dependent variables)


Independent variables included in the best model

Pons

Medulla oblongata

Cerebellum

Mesencephalon

Diencephalon

Telencephalon


Total brain volume minus the dependent variable

b = 1.233

b = 0.734

b = 1.030

b = 0.646

b = 0.841

b = 1.090

t = 21.016

t = 17.239

t = 22.734

t = 20.520

t = 30.225

t = 28.424

p << 0.001

p << 0.001

p << 0.001

p << 0.001

p << 0.000

p << 0.001

Sexual size dimorphism

b = -0.240

b = 0.369

-

b = 0.168

b = 0.140

b = -0.182

t = -2.421

t = 5.093

t = 3.134

t = 3.294

t = -3.227

p = 0.026

p << 0.001

p = 0.006

p = 0.005

p = 0.005

Female group size

--

--

--

--

b = -0.064

b = 0.119

t = -2.143

t = 3.259

p = 0.048

p = 0.005

Male group size

--

--

--

--

b = 0.043

b = -0.062

t = 2.021

t = -2.335

p = 0.060

p = 0.033


Whole model

F(2,18) = 258.21

F(2, 18) = 260.89

F(1,19) = 516.82

F(2,18) = 317.32

F(4,16) = 409.56

F(4,16) = 352.48

R2 = 0.966

R2 = 0.967

R2 = 0.964

R2 = 0.972

R2 = 0.990

R2 = 0.989

p << 0.001

p << 0.001

p << 0.001

p << 0.001

p << 0.001

p << 0.001


The table shows results from separate multiple regression models based on independent contrasts investigating the effects of four independent variables on six different main components of the primate brain.

The models were constructed by sequentially removing variables, keeping those with p ≤ 0.1. Each column contains one best regression model relating to that specific brain component. Numbers to the right of each independent variable are the partial regression coefficients for that specific variable, and the numbers in the bottom row give statistics for the multiple regression models. Dashes indicate variables excluded from the final best models because they had a partial regression p > 0.1.

Lindenfors et al. BMC Biology 2007 5:20   doi:10.1186/1741-7007-5-20

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