Advertisement

Parrondo's paradox calculator

Compare two capital-dependent games with their combination. This model calculates expected gains directly, rather than displaying one random simulation.

Calculator

Expected gain from A alone
-1.000000
Expected gain from B alone
-1.392320
Expected gain from combined games
1.287327
Expected final combined capital
1.287327
Expected cumulative gains
RoundA aloneB aloneCombined
1.000000-0.010000-0.810000-0.410000
2.000000-0.020000-0.320000-0.170000
3.000000-0.030000-0.737985-0.286980
4.000000-0.040000-0.393033-0.186860
5.000000-0.050000-0.709709-0.227018
6.000000-0.060000-0.449881-0.173618
7.000000-0.070000-0.692737-0.183588
8.000000-0.080000-0.497232-0.150322
9.000000-0.090000-0.684001-0.146654
10.000000-0.100000-0.537406-0.122692
11.000000-0.110000-0.681523-0.112656
12.000000-0.120000-0.572124-0.093061
13.000000-0.130000-0.683804-0.080027
14.000000-0.140000-0.602690-0.062490
15.000000-0.150000-0.689704-0.048044
16.000000-0.160000-0.630101-0.031476
17.000000-0.170000-0.698356-0.016365
18.000000-0.180000-0.655112-0.000253
19.000000-0.190000-0.7091010.015171
20.000000-0.200000-0.6782980.031067
21.000000-0.210000-0.7214380.046640
22.000000-0.220000-0.7000960.062435
23.000000-0.230000-0.7349860.078077
24.000000-0.240000-0.7208380.093823
25.000000-0.250000-0.7494540.109498
26.000000-0.260000-0.7407770.125223
27.000000-0.270000-0.7646210.140913
28.000000-0.280000-0.7601060.156627
29.000000-0.290000-0.7803220.172325
30.000000-0.300000-0.7789700.188033
31.000000-0.310000-0.7964270.203734
32.000000-0.320000-0.7974820.219441
33.000000-0.330000-0.8128400.235144
34.000000-0.340000-0.8157250.250849
35.000000-0.350000-0.8294870.266552
36.000000-0.360000-0.8337640.282257
37.000000-0.370000-0.8463120.297961
38.000000-0.380000-0.8516470.313665
39.000000-0.390000-0.8632730.329369
40.000000-0.400000-0.8694130.345074
41.000000-0.410000-0.8803370.360778
42.000000-0.420000-0.8870890.376482
43.000000-0.430000-0.8974790.392186
44.000000-0.440000-0.9046960.407891
45.000000-0.450000-0.9146800.423595
46.000000-0.460000-0.9222510.439299
47.000000-0.470000-0.9319270.455003
48.000000-0.480000-0.9397670.470708
49.000000-0.490000-0.9492080.486412
50.000000-0.500000-0.9572530.502116
51.000000-0.510000-0.9665150.517820
52.000000-0.520000-0.9747160.533524
53.000000-0.530000-0.9838430.549229
54.000000-0.540000-0.9921620.564933
55.000000-0.550000-1.0011850.580637
56.000000-0.560000-1.0095950.596341
57.000000-0.570000-1.0185390.612046
58.000000-0.580000-1.0270170.627750
59.000000-0.590000-1.0359020.643454
60.000000-0.600000-1.0444320.659158
61.000000-0.610000-1.0532710.674862
62.000000-0.620000-1.0618410.690567
63.000000-0.630000-1.0706460.706271
64.000000-0.640000-1.0792460.721975
65.000000-0.650000-1.0880240.737679
66.000000-0.660000-1.0966470.753384
67.000000-0.670000-1.1054060.769088
68.000000-0.680000-1.1140460.784792
69.000000-0.690000-1.1227890.800496
70.000000-0.700000-1.1314420.816200
71.000000-0.710000-1.1401740.831905
72.000000-0.720000-1.1488380.847609
73.000000-0.730000-1.1575610.863313
74.000000-0.740000-1.1662320.879017
75.000000-0.750000-1.1749480.894722
76.000000-0.760000-1.1836250.910426
77.000000-0.770000-1.1923360.926130
78.000000-0.780000-1.2010180.941834
79.000000-0.790000-1.2097250.957539
80.000000-0.800000-1.2184100.973243
81.000000-0.810000-1.2271140.988947
82.000000-0.820000-1.2358021.004651
83.000000-0.830000-1.2445041.020355
84.000000-0.840000-1.2531931.036060
85.000000-0.850000-1.2618941.051764
86.000000-0.860000-1.2705841.067468
87.000000-0.870000-1.2792841.083172
88.000000-0.880000-1.2879751.098877
89.000000-0.890000-1.2966741.114581
90.000000-0.900000-1.3053661.130285
91.000000-0.910000-1.3140641.145989
92.000000-0.920000-1.3227571.161693
93.000000-0.930000-1.3314541.177398
94.000000-0.940000-1.3401481.193102
95.000000-0.950000-1.3488451.208806
96.000000-0.960000-1.3575391.224510
97.000000-0.970000-1.3662351.240215
98.000000-0.980000-1.3749291.255919
99.000000-0.990000-1.3836261.271623
100.000000-1.000000-1.3923201.287327

Advertisement

How this calculator works

Game A wins one unit with probability 0.5 - epsilon. Game B uses probability 0.1 - epsilon when capital is divisible by three and 0.75 - epsilon otherwise. A loss costs one unit; capital may become negative, with no absorbing bankruptcy rule. The calculator tracks probabilities of the three capital remainders and the expected reward each round. Random mixing changes the state distribution, so its gain is not a weighted average of the standalone long-run gains. Short runs and some mixtures need not exhibit the paradox.

Formula

p_A = 1/2 - epsilon. p_B(0) = 1/10 - epsilon; p_B(1) = p_B(2) = 3/4 - epsilon. Random mixture: p_r = gamma p_A + (1 - gamma)p_B(r). Expected one-step gain = sum_r probability(r)(2p_r - 1).

Worked example

With epsilon zero and starting capital zero, game A has first-step expected gain 0 and game B has gain -0.8. A 50:50 random mixture has gain -0.4 on that first step. With epsilon 0.005 over longer runs, mixing can reverse the standalone losses.

Advertisement

Frequently asked questions

Does combining any two losing games make a winner?

No. The state dependence and switching rule are essential. Many combinations remain losing.

Can a player go bankrupt in this model?

Capital is allowed to take any integer value. A stopping rule at zero would change the state process and the expected gains.

Is the table one simulated path?

No. Each entry is an expected gain obtained by propagating probabilities. Individual play can differ greatly from the expectation.

Sources

Advertisement