a) The proportion of people in a given community who have Covid- 19 infection is 0.005. A test is available to diagnose the disease. If a person has Covid-19, the probability that the test will produce a positive signal is 0.99. If a person does not have the Covid-19, the probability that the test will produce a positive signal is 0.01. if a 2 person tests positive, what is the probability that the person actually has the Covid-19 infection? i. Which model will best be good for solving the above problem and why? ii. In your own words, comment on the types of events you see in the problem and name them. b) 30% of people who seek psychotherapy will recover from their symptoms irrespective of whether they receive treatment. A research finds that a particular type of psychotherapy is successful with 45 out of 100 clients. Using an alpha level of 0.05 as a criterion, what should she conclude about the effectiveness of this psychotherapeutic approach? i. Which statistical model is most likely to be used by the researcher to investigate the issue at hand and why? A s] What contribution does the alpha level make, in determining a decision on the effectiveness of the psychotherapeutic approach? ii. ARI2 markc)
Addition Rule of Probability
It simply refers to the likelihood of an event taking place whenever the occurrence of an event is uncertain. The probability of a single event can be calculated by dividing the number of successful trials of that event by the total number of trials.
Expected Value
When a large number of trials are performed for any random variable ‘X’, the predicted result is most likely the mean of all the outcomes for the random variable and it is known as expected value also known as expectation. The expected value, also known as the expectation, is denoted by: E(X).
Probability Distributions
Understanding probability is necessary to know the probability distributions. In statistics, probability is how the uncertainty of an event is measured. This event can be anything. The most common examples include tossing a coin, rolling a die, or choosing a card. Each of these events has multiple possibilities. Every such possibility is measured with the help of probability. To be more precise, the probability is used for calculating the occurrence of events that may or may not happen. Probability does not give sure results. Unless the probability of any event is 1, the different outcomes may or may not happen in real life, regardless of how less or how more their probability is.
Basic Probability
The simple definition of probability it is a chance of the occurrence of an event. It is defined in numerical form and the probability value is between 0 to 1. The probability value 0 indicates that there is no chance of that event occurring and the probability value 1 indicates that the event will occur. Sum of the probability value must be 1. The probability value is never a negative number. If it happens, then recheck the calculation.
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