Q&A for How to Calculate Variance

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  • Question
    What are deviations?
    Mario Banuelos, PhD
    Associate Professor of Mathematics
    Mario Banuelos is an Associate Professor of Mathematics at California State University, Fresno. With over eight years of teaching experience, Mario specializes in mathematical biology, optimization, statistical models for genome evolution, and data science. Mario holds a BA in Mathematics from California State University, Fresno, and a Ph.D. in Applied Mathematics from the University of California, Merced. Mario has taught at both the high school and collegiate levels.
    Associate Professor of Mathematics
    Expert Answer
    A deviation is the distance of an observation or a data point from the mean, or the center of all the data points. it gives you a sense of how spread apart the data is from the mean.
  • Question
    What is the easiest way to find variance?
    Mario Banuelos, PhD
    Associate Professor of Mathematics
    Mario Banuelos is an Associate Professor of Mathematics at California State University, Fresno. With over eight years of teaching experience, Mario specializes in mathematical biology, optimization, statistical models for genome evolution, and data science. Mario holds a BA in Mathematics from California State University, Fresno, and a Ph.D. in Applied Mathematics from the University of California, Merced. Mario has taught at both the high school and collegiate levels.
    Associate Professor of Mathematics
    Expert Answer
    First, calculate the mean or average of all of the data points. Then, calculate the difference between each data point and that mean. Square each of those differences, add them all up, then divide them by n (the total number of data points) minus 1.
  • Question
    How do I calculate the variance of four numbers?
    Community Answer
    Follow these steps: Work out the mean (the simple average of the numbers.) Then, for each number, subtract the mean and square the result (the squared difference). Finally, work out the average of those squared differences.
  • Question
    If the coefficient of variance is 16 and mean is 25, how do I find the variance?
    Community Answer
    Coefficience of variance = (std dev / mean) * 100. 16 = (std dev / 25) * 100. Std dev = 4. Variance = (std dev)^2 = 16.
  • Question
    How do I calculate the standard deviation?
    Community Answer
    Standard deviation is the square root of the variance.
  • Question
    What is a coefficient of variance?
    Community Answer
    Coefficient of variance is ratio of standard deviation to mean. CV% = SD/mean * 100.
  • Question
    If the standard deviation is 4, the variance is what?
    Community Answer
    16. The square of 4 is 16, and the variance is the square of the standard deviation.
  • Question
    What does it mean by inter quartile range?
    Community Answer
    This is the difference between the upper quartile and the lower quartile.
  • Question
    How do I find the variance of a large number?
    Community Answer
    If you have a lot of figures, the best way to find the variance is too use excel. Therefore, you might as well look directly for the standard deviation as the variance's only use is too calculate standard deviation.
  • Question
    How do I improve my math skills?
    Community Answer
    Try the methods in Improve Math Skills .
  • Question
    How do I calculate population variance?
    Community Answer
    First find mean for population, then subtract mean from each value squared divide answer by number of variable in a population.
  • Question
    How do I calculate the variance of a frequency distribution table?
    Community Answer
    Method 1 above shows you what to do. Namely: 1. Calculating the sample mean, 2. Subtract the sample mean to each number you are given, 3. Square each result, 4. Add all the values, 5. Divide it by the sample mean minus 1.
  • Question
    How do I calculate variance for grouped data?
    Community Answer
    Find the midpoint of the class first and then use that as your x value for step two.
  • Question
    How do you describe standard deviation?
    Donagan
    Top Answerer
    It's a measure of how much a set of numbers varies from the average number in the set.
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