[Series 65] 12, Descriptive Statistics and Correlation

0:00We are covering descriptive statistics for the Series 65 exam, focusing on measures of central tendency, volatility, and correlation. For the exam, you need to understand mean, median, and mode as they apply to a set of investment returns. The mean is simply the average return. The median is the middle value when the returns are listed in order, which is important because it's less skewed by extremely high or low returns or outliers. The mode is the most frequently occurring return in the data set. The exam might present a series of annual returns for a mutual fund and ask you to identify one of these measures. For example, if a fund has returns of 5%, 7%, 7%, 9%, and 12%, the mean is 8%, the median is 7%, and the mode is also 7%. A common exam trap is to confuse these three, especially when a single outlier pulls the mean away from the median. Remember, the median is often a better indicator

1:02of the typical return in a skewed distribution. Next, we have standard deviation and variance, which are critical for understanding investment risk. Variance measures the dispersion of returns from the average return, but the exam focuses more on its square root, the standard deviation. For the Series 65, you must know that a higher standard deviation means greater volatility and therefore greater risk. You won't likely need to calculate it, but you'll need to interpret it. For instance, a question might show two portfolios. The one with the lower standard deviation is the less volatile and more conservative choice. The exam frequently tests the concept of a normal distribution or bell curve where approximately 67% of returns fall within one standard deviation of the mean and 95% fall within two standard deviations. A typical question might state a fund's average return is 10% with a standard deviation of 5%,

2:03then ask for the range of returns expected 95% of the time. The answer would be between 0% and 20%. Finally, let's discuss the correlation coefficient, which ranges from negative one to positive one. This number measures the degree to which two investments move in relation to each other. A correlation of positive one means they move in perfect lock step, while negative one means they move in exact opposite directions. A correlation of zero means there is no linear relationship between their movements. In portfolio analysis, the goal of diversification is to combine assets with low or ideally negative correlation to reduce overall portfolio risk. The exam will test this by asking how to best diversify a portfolio. For instance, if you have a stop portfolio, adding an asset with a correlation of negative 0.8 would provide better diversification than adding one with a correlation of positive 0.8. A common trap is assuming that a zero correlation

3:04means no relationship at all. It specifically means no linear relationship. For a memorable phrase, remember this. Correlation is for diversification. Standard deviation is for volatility. This simple statement connects the core application of each concept for the exam. For free practice questions, AI-powered explanations, and more exam prep tools, visit openexamprep.com. That's openexamprepalloneword.com.