Time 0
|
10000
|
0
|
0
|
0
|
0
|
Start using A
|
250 i → ii
| | | | |
Start using B
|
500 i → iii
| | | | |
Time 1
|
10000 − 250 − 500 = 9250
|
250
|
500
|
0
|
0
|
Start using A
|
231 i → ii
| |
13 iii → v
| | |
Start using B
|
463 i → iii
|
13 ii → iv
| | | |
Time 2
|
9250 − 231 − 463 = 8556
|
250 + 231 − 13 = 469
|
500 + 463 − 13 = 950
|
13
|
13
|
Start using A
|
214 i → ii
| |
24 iii → v
| | |
Start using B
|
428 i → iii
|
23 ii → iv
| | | |
Time 3
|
8556 − 214 − 428 = 7915
|
469 + 214 − 23 = 659
|
950 + 428 − 24 = 1354
|
13 + 23 = 36
|
13 + 24 = 36
|
Start using A
|
198 i → ii
| |
34 iii → v
| | |
Start using B
|
396 i → iii
|
33 ii → iv
| | | |
Time 4
|
7915 − 198 − 396 = 7321
|
659 + 198 − 33 = 824
|
1354 + 396 − 34 = 1716
|
36 + 33 = 69
|
36 + 34 = 70
|
P1: Proportion who start B among A first users
|
69/(824 + 69)
|
=0.08
|
P2: Proportion who start B among others
|
(1716 + 70)/(7321 + 1716 + 70)
|
=0.20
|
P3: Proportion who start B among never A users
|
1716/(7321 + 1716)
|
=0.19
|
OR1 as defined in (using P1 and P2)
|
(0.08/(1-0.08))/(0.20/(1-0.20))
|
=0.34
|
OR2 as defined in (using P1 and P3)
|
(0.08/(1-0.08))/(0.19/(1-0.19))
|
=0.36
|
RR stratified by period (using columns i and ii)
|
Period 1–2
|
(13/250)/(463/9250)
|
=1
|
|
Period 2–3
|
(23/469)/(428/8556)
|
=1
|
|
Period 3–4
|
(33/659)/(396/7915)
|
=1
|