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Table 4 Analysis of Covariance (Regression Equation)

From: International Physical Activity Questionnaire (IPAQ) and New Zealand Physical Activity Questionnaire (NZPAQ): A doubly labelled water validation

Set 1

   

Dependent Variable (Y):

DLW average daily activity-related EE (kJ)

Independent Variable (X):

IPAQ average daily activity-related EE (kJ)

Parameter

Estimate

StdErr

p-value (t-test)

Intercept

2137.01

497.95

0.000

IPAQAEE

0.52

0.16

0.002

R2 = 0.25

   

Regression Line: DLWAEE = 2137 + 0.52 * IPAQ

With covariates

   

Intercept

-2082.47

2009.59

0.31

IPAQAEE

0.45

0.15

0.006

Male

-2589

830.44

0.017

FFM

97.37

42.24

0.028

R2 = 0.38

   

Regression Line: DLWAEE = -2082 + 0.45 * IPAQAEE + 2589 * sex + 97 * FFM

Set 2

   

Dependent Variable (Y):

DLW average daily activity-related EE (kJ)

Independent Variable (X):

NZPAQ-SF average daily activity-related EE (kJ)

Parameter

Estimate

StdErr

p-value (t-test)

Intercept

1885.39

440.40

0.0001

NZPAQAEE

1.18

0.24

0.0001

R2 = 0.38

   

Regression Line: DLW = 1885 + 1.18 * NZPAQAEE

Set 3

   

Dependent Variable (Y):

IPAQ-LF average daily activity-related EE (kJ)

Independent Variable (X):

NZPAQ-SF average daily activity-related EE (kJ)

Parameter

Estimate

StdErr

p-value (t-test)

Intercept

848.32

360.67

0.037

NZPAQAEE

1.18

0.22

0.0001

R2 = 0.47

   

Regression Line: IPAQ = 848 + 1.18 * NZPAQ

With covariates

   

Intercept

-1135.67

1080.36

0.30

NZPAQAEE

1.25

0.21

0.0001

Age

49.09

25.06

0.05

R2 = 0.53

   

Regression Line: IPAQAEE = -1135 + 1.25 * NZPAQAEE + 49 * Age