Calculating EV is a very useful tool in investments and stock market predictions. As with any EV problem, you must begin by defining all possible outcomes. Generally, real world situations are not as easily definable as something like rolling dice or drawing cards. For that reason, analysts will create models that approximate stock market situations and use those models for their predictions. Suppose, for this example, that you can define 4 distinct results for your investment. These results are:  1. Earn an amount equal to your investment 2. Earn back half your investment 3. Neither gain nor lose 4. Lose your entire investment In some cases, you may be able to assign a specific dollar value to the possible outcomes. Other times, in the case of a model, you may need to assign a value or score that represents monetary amounts. In the investment model, for simplicity, assume you invest $1. The assigned value of each outcome will be positive if you expect to earn money and negative if you expect to lose. In this problem, the four possible outcomes therefore have the following values, relative to the $1 investment:  1. Earn an amount equal to your investment = +1 2. Earn back half your investment = +0.5 3. Neither gain nor lose = 0 4. Lose your entire investment = -1 In a situation like the stock market, professional analysts spend their entire careers trying to determine the likelihood that any given stock will go up or down on any given day. The probability of the outcomes usually depends on many external factors. Statisticians will work together with market analysts to assign reasonable probabilities to prediction models. For this example, assume that the probability of each of the four outcomes is equal, at 25%. Use your list of all possible outcomes, and multiply each value times the probability of that value occurring. For the model investment situation, these calculations would look like this:  1. Earn an amount equal to your investment = +1 * 25% = 0.25 2. Earn back half your investment = +0.5 * 25% =...

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Write a summary of the previous text in Chinese:
确定所有可能的结果。 为每种可能的结果赋值。 确定每种结果的概率。 将每个结果值乘以其各自的概率。 所有乘积加总求和。 理解结果。