Contingency table.

Contingency table for simulated data where the expected frequency count for each cell of the table is at least 5. The rows represent the average viremia after 4 weeks from treatment interruption in logarithmic scale. The columns represent the two groups in which HAART starts during chronic phase (late) or within the first 20 days (very-early). The null hypothesis states that knowing the start timing does not help to predict . That is, the events are independent. Support for the alternative hypothesis suggests that the two events are related. The value found rejects the null hypothesis.