Match Algorithm

Age Caliper

GCP Caliper

Number of Pairs

Number Cases/Controls^{b}

Mean Distance

Sum of Distance


Greedy

1

1

8

7/6/1

1.02

8.15

Optimal

1

1

8

7/6/1

1.02

8.15

Greedy

2

2

28

21/14/7

1.90

53.29

Optimal

2

2

28

21/14/7

1.90

53.29

Greedy

3

3

38

26/14/12

2.28

86.54

Optimal

3

3

38

26/14/12

2.28

86.63

Greedy

4

4

48

32/16/16

2.87

137.9

Optimal

4

4

49

33/17/16

2.97

145.7

Greedy

5^{a}

5

56

34/12/22

3.47

194.4

Optimal

5^{a}

5

60

36/12/24

3.91

234.4

Greedy

6

6

62

37/12/25

3.98

247.1

Optimal

6

6

67

39/11/28

4.27

286.1


^{a}Caliper is defined to be the minimum allowable difference between the case and the control. In our study, we used a caliper of five for age and GCP, and zero for the other four categorical variables

GCP general cognitive performance

^{b}There are three numbers listed in this column, for example 7/6/1 means seven cases were matched, six cases matched to 1:1, so six controls; and one case matched to 1:2, so two controls. This gives a total of eight matched pairs