Sunday, February 9, 2014

Lesson summary for Wednesday, 5th February

We did a quiz and went revised what standard deviation is.

Standard deviation (σ is the symbol, is a measure of the variance from the mean for a set of data. It is calculated as follows:

x̄ (pronounced as x bar) is the mean of the data set.
n is the number of data in the set.
Σ, or summation, is the addition of all the following datum. In this case, it is (x-x̄)^2.

Showing the proper working during the examples is essential to getting the method mark(s).

For example,

Calculate the mean, median and standard deviation for the following set of data.


mean = (1+2+3)/3
     = 3

Tmedian = (3+1)/2
        = 2
median = 2
standard deviation = √(  (  (1-2)^2  +  (2-2)^2  +  (3-2)^2  ) / 2  )
                   = 1

The standard deviation’s and mean’s working can be in the form of a table containing all the data, and you can just use the values of Σ(x-x̄), n and Σx to calculate your answers.

If there are UNITS in the question, be sure to write them down in your answers as well.

Other reminders:

- Write scale when drawing graphs
- Show ALL the working when calculating the standard deviation, mean and median.

Check out these G+ posts to learn how to use STAT functions in your calculator

p.s. Sorry for the late post!

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