The Role of Probability. Basic Concepts of Probability. A probability is a number that reflects the chance or likelihood that a particular event will occur. Probabilities can be expressed as proportions that range from 0 to 1, and they can also be expressed as percentages ranging from 0% to 100%.
Thus, when people hypoventilate (i.e. causing an increase in CO2) this causes the pH in your blood to decrease, making it more acidic. (and when hyperventilation occurs, O2 is increased, which causes an increase in pH - making blood more basic).
During the early stages of hypoventilation with mild to moderate hypercapnia, patients usually are asymptomatic or have only minimal symptoms. Patients may be anxious and complain of dyspnea with exertion. As the degree of hypoventilation progresses, patients develop dyspnea at rest.