Log in Tais Price 8 years agoPosted 8 years ago. Direct link to Tais Price's post “What are the steps to fin...” What are the steps to finding the square root of 3.5? I can't figure out how to get to 1.87 with out knowing the answer before hand. • (26 votes) katie <3 4 years agoPosted 4 years ago. Direct link to katie <3's post “without knowing the squar...” without knowing the square root before hand, i'd say just use a graphing calculator (25 votes) Shannon 7 years agoPosted 7 years ago. Direct link to Shannon's post “But what actually is stan...” But what actually is standard deviation? I understand how to get it and all but what does it actually tell us about the data? • (18 votes) ZeroFK 7 years agoPosted 7 years ago. Direct link to ZeroFK's post “The standard deviation is...” The standard deviation is a measure of how close the numbers are to the mean. If the standard deviation is big, then the data is more "dispersed" or "diverse". As an example let's take two small sets of numbers: akanksha.rph 8 years agoPosted 8 years ago. Direct link to akanksha.rph's post “I want to understand the ...” I want to understand the significance of squaring the values, like it is done at step 2. Why actually we square the number values? • (12 votes) Matthew Daly 8 years agoPosted 8 years ago. Direct link to Matthew Daly's post “The important thing is th...” The important thing is that we want to be sure that the deviations from the mean are always given as positive, so that a sample value one greater than the mean doesn't cancel out a sample value one less than the mean. There are two strategies for doing that, squaring the values (which gives you the variance) and taking the absolute value (which gives you a thing called the Mean Absolute Deviation). Even though taking the absolute value is being done by hand, it's easier to prove that the variance has a lot of pleasant properties that make a difference by the time you get to the end of the statistics playlist. (20 votes) jkcrain12 8 years agoPosted 8 years ago. Direct link to jkcrain12's post “From the class that I am ...” From the class that I am in, my Professor has labeled this equation of finding standard deviation as the population standard deviation, which uses a different formula from the sample standard deviation. Is there a way to differentiate when to use the population and when to use the sample? Or would such a thing be more based on context or directly asking for a giving one? Why do we use two different types of standard deviation in the first place when the goal of both is the same? • (11 votes) sarah ehrenfried 4 years agoPosted 4 years ago. Direct link to sarah ehrenfried's post “The population standard d...” The population standard deviation is used when you have the data set for an entire population, like every box of popcorn from a specific brand. Having this data is unreasonable and likely impossible to obtain. That's why the sample standard deviation is used. Sample standard deviation is used when you have part of a population for a data set, like 20 bags of popcorn. This is much more reasonable and easier to calculate. (4 votes) G. Tarun 5 years agoPosted 5 years ago. Direct link to G. Tarun's post “What is the formula for c...” What is the formula for calculating the variance of a data set? Is it the same as the formula for standard deviation given in this article but without the square root? • (6 votes) Ian Pulizzotto 5 years agoPosted 5 years ago. Direct link to Ian Pulizzotto's post “Yes, the standard deviati...” Yes, the standard deviation is the square root of the variance. (8 votes) origamidc17 8 years agoPosted 8 years ago. Direct link to origamidc17's post “If I have a set of data w...” If I have a set of data with repeating values, say 2,3,4,6,6,6,9, would you take the sum of the squared distance for all 7 points or would you only add the 5 different values? • (7 votes) chung.k2 6 years agoPosted 6 years ago. Direct link to chung.k2's post “In the formula for the SD...” In the formula for the SD of a population, they use mu for the mean. Is there a difference from the x with a line over it in the SD for a sample? • (5 votes) Cody Cox 6 years agoPosted 6 years ago. Direct link to Cody Cox's post “No, μ and x̄ mean the sam...” No, μ and x̄ mean the same thing (no pun intended). At least when it comes to standard deviation. (9 votes) ANGELINA569 6 years agoPosted 6 years ago. Direct link to ANGELINA569's post “I didn't get any of it. I...” I didn't get any of it. I need help really badly. What does this stuff mean? • (6 votes) Sergio Barrera 4 years agoPosted 4 years ago. Direct link to Sergio Barrera's post “It may look more difficul...” It may look more difficult than it actually is, because (5 votes) Madradubh 7 years agoPosted 7 years ago. Direct link to Madradubh's post “Hi,How do I calculate th...” Hi, • (7 votes) cossine 2 years agoPosted 2 years ago. Direct link to cossine's post “You would have a covarian...” You would have a covariance matrix. You could find the Cov that is covariance. E.g. Cov(X, X) = Var(X) = standard_deviation_x^2 Similarly we could do the same thing for Y. We can also find Cov(X, Y). Just use definition. If you are not able find it on khan academy just go to Wikipedia. (1 vote) Michael McConnell a year agoPosted a year ago. Direct link to Michael McConnell's post “What is the name of the s...” What is the name of the symbol for mean? • (5 votes) rudro.saha.195 a year agoPosted a year ago. Direct link to rudro.saha.195's post “Mu (Greek letter)” Mu (Greek letter) (6 votes)Want to join the conversation?
4.9, 5.1, 6.2, 7.8
and
1.6, 3.9, 7.7, 10.8
The average (mean) of both these sets is 6. But the second set is more dispersed: the numbers are further away from the mean.
This is reflected in the standard deviation: if I calculated correctly (please check!) the first set has a standard deviation of 2.3, the second has 7.05.
In other words, is standard deviation the square root of the variance?
I remember vaguely that one of the two — SD and variance — is the square (or square root) of the other.
all the different variables that are used are just there to represent the numbers in your equation. Therefore, those variables are just examples of how to solve for Standard Deviation, and are not actually in the equation.
How do I calculate the standard deviation of bivariate data by hand?
Thanks
Sean
