If you flip a coin many times, it will be heads half the time and tails half the time. The probability (==chance) of heads for any flip is 0.5 (pH=0.5), while the probability of tails for any flip is 0.5 (pT=0.5).
 | Note |
|---|---|
| pH+pT=1.0, i.e. you've accounted for all possible outcomes. | |
If you flip two separate coins (or equivalently the same coin twice), and observe the outcomes you'll find the following.
Table 11. Two coin toss, results for 2nd toss
| Result for 1st coin | Result for 2nd coin |
|---|---|
| heads | pH=0.5, pT=0.5 |
| tails | pH=0.5, pT=0.5 |
This result should be so obvious that you wonder why it's mentioned. The results demonstrate the outcomes of independant events (here coin tosses). The fact that the results of each coin toss are independant, allows us to construct this table.
Table 12. Outcomes from two coin toss
| Result for 1st coin | Result for 2nd coin | Result for 2nd coin | Result for 2nd coin |
|---|---|---|---|
| heads | pH=0.5, pT=0.5 | pH=0.5, pT=0.5 | pH=0.5, pT=0.5 |
| tails | pH=0.5, pT=0.5 | pH=0.5, pT=0.5 | pH=0.5, pT=0.5 |