In finance, risk of investments may be measured by calculating the variance and standard deviation of the distribution of returns on those investments. Variance measures how far in either direction the amount of the returns may deviate from the mean.
1. Standard deviation is not a measure of variance: it is the square root of the variance.2. The answer depends on better than WHAT!
How do we calculate variance
the variance
They are measures of the spread of distributions about their mean.
In finance, risk of investments may be measured by calculating the variance and standard deviation of the distribution of returns on those investments. Variance measures how far in either direction the amount of the returns may deviate from the mean.
The standard deviation or volatility (square root of the variance) of returns.
Variance
The total risk of a single asset is measured by the standard deviation of return on asset. Standard deviation is the square root of variance. To measure variance, you must have some distribution/ possibility of asset returns. However, the relevant risk of a single asset is the systematic risk, not the total risk. Systematic risk is the risk that cannot be diversified away in a portfolio. Systematic risk of an asset is measured by the Beta. Beta can be found using Regression (between market return and asset's return) or Covariance formula.
1. Standard deviation is not a measure of variance: it is the square root of the variance.2. The answer depends on better than WHAT!
How do we calculate variance
A variance is a measure of how far a set of numbers is spread out around its mean.
Equal Variance
It means you can take a measure of the variance of the sample and expect that result to be consistent for the entire population, and the sample is a valid representation for/of the population and does not influence that measure of the population.
It is the variance in time between each heartbeat. ECG, and blood pressure tests are often used to measure the variance in the rhythm of the heart.
Variance is a measure of "relative to the mean, how far away does the other data fall" - it is a measure of dispersion. A high variance would indicate that your data is very much spread out over a large area (random), whereas a low variance would indicate that all your data is very similar.Standard deviation (the square root of the variance) is a measure of "on average, how far away does the data fall from the mean". It can be interpreted in a similar way to the variance, but since it is square rooted, it is less susceptible to outliers.
Yes, but negative variance indicates environmental variance (i.e., within-family or within-strain) is unusually high, possibly due to poor experimental design. Narrow sense heritability (h2, not H2) = (phenotypic variance - environmental variance) / phenotypic variance.