Skip to main content

Table 3 DIF analysis: CHI SQUARE values for overall DIF (model 3-model1) with uniform and non-uniform DIF identified

From: Exploring differential item functioning in the SF-36 by demographic, clinical, psychological and social factors in an osteoarthritis population

Item

Age

Gender

Social class

Social deprivation

Employ

Mood

BMI

No. joints

Hip/Knee

Physical functioning

         

PF1 vigorous activities

19.21 NU

2.26

1.26

5.24

3.99

0.23

13.80 NU

0.99

0.93

PF2 moderate activities

1.98

1.32

5.90

5.15

1.47

3.93

0.21

4.77

1.50

PF3 lift/carry groceries

0.53

29.08 U *

1.13

0.39

2.40

1.90

1.03

2.53

2.98

PF4 several flight stairs

1.96

10.17

4.24

5.17

5.14

4.94

2.13

3.00

5.63

PF5 one flight stairs

2.87

0.49

2.33

1.91

0.79

0.54

3.31

1.44

1.67

PF6 bend/knee/stoop

16.73 NU

5.58

4.74

2.31

4.42

1.21

5.43

1.024

0.21

PF7 walk more mile

4.04

2.63

2.85

0.92

2.75

2.09

0.85

1.39

0.65

PF8 walk half mile

0.37

0.41

3.37

3.01

1.02

1.48

0.50

0.57

7.25

PF9 walk 100 yards

10.73

0.20

2.87

6.53

0.00

3.01

2.40

4.07

0.81

PF10 bathing or dressing

1.01

4.36

2.04

3.71

11.01

12.67

6.26

1.80

1.49

Pain

         

P1 intensity of bodily pain

8.55

0.24

8.21

1.60

32.45 NU *

4.65

4.10

0.73

4.59

P2 extent pain interfere normal work

5.78

7.66

10.34 U/NU *

5.0

10.27

5.92

2.05

0.99

7.18

Role physical

         

RP1 cut down time on work/act.

1.74

0.63

4.20

10.26 NU *

17.13 NU *

0.44

0.05

2.65

9.18 NU

RP2 accomplished less

10.98 U

1.05

1.43

0.89

0.72

0.48

0.44

2.55

4.14

RP3 limited in kind of work/activities

1.58

2.08

1.75

3.62

0.72

8.57

0.28

6.54

0.16

RP4 difficulty performing work/act.

2.10

1.69

2.80

1.04

10.52 U

5.42

0.15

1.26

0.80

Social functioning

         

SF1 interferes with social activities

14.95 NU

3.82

9.05

0.87

19.50 NU *

0.43

1.71

0.74

1.46

SF2 time interferes with social act.

9.67

9.57

1.33

5.95

7.16

4.80

1.83

0.22

4.78

Role emotional

         

RE1 cut down time work/activities

0.42

0.25

5.75

1.40

1.14

0.12

1.03

0.32

0.97

RE2 accomplished less

6.68

0.35

0.18

2.00

6.45

4.06

3.46

5.45

9.32 *

Not as careful work/activities

6.94

1.15

1.66

2.30

2.66

5.00

4.85

4.21

0.97

Mental

         

MH1 nervous

3.05

14.50 U *

4.19

0.74

5.40

18.11 NU *

1.53

4.24

2.31

MH2 down in dumps

4.14

0.98

12.31 U *

0.65

0.95

7.28

6.96

2.32

1.24

MH3 calm and peaceful

8.48

6.54

1.23

4.00

6.36

46.33 NU *

11.48

4.63

9.75

MH4 downhearted and low

2.39

1.11

4.13

10.24

5.09

14.35 NU *

8.22

0.02

1.29

MH5 happy person

0.93

1.64

8.36

3.18

9.18

47.19 NU *

3.82

0.27

2.60

Vitality

         

V1 full of life

6.93

0.16

3.25

7.25

4.56

7.48

3.09

4.95

0.28

V2 energy

10.91 U

0.36

0.17

1.10

1.67

5.35

2.57

2.70

0.44

V3 worn out

8.82 U

0.33

0.05

3.25

10.45 U

0.34

1.68

4.38

0.45

V4 tired

5.49

8.19

2.48

2.20

7.07

2.59

0.20

0.91

0.88

General health

         

GH1 health in general

9.12

2.30

6.04

2.21

8.77

3.05

1.49

2.48

2.66

GH2 get ill more easily than others

2.26

3.70

1.01

6.64

1.39

12.03 U *

1.62

3.71

3.16

GH3 as healthy as anybody I know

2.47

5.74

6.31

2.51

5.02

3.97

2.41

2.10

0.26

GH4 except health to get worse

4.36

10.26

6.61

10.71

4.47

3.46

1.68

4.12

2.41

GH5 my health is excellent

0.94

1.05

0.91

2.49

1.10

9.85

2.77

7.90

0.23

  1. Where the item has been dichotomised, the larger value is entered in the table.
  2. KEY: U = uniform. NU = non-uniform, * = still significant after adjusting for age.
  3. Boldface=significant DIF.
Back to article page

BMC Musculoskeletal Disorders

ISSN: 1471-2474

Contact us