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Linear Regression Analysis Paper

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Welcome Back LV Team,

Today, we are going to look at variability. Before we do that, let us review our last week session. The central tendency can be measured in three ways: mean, median, mode. The mean is the more precise, then median and lastly mode. Each of them provides different type of information about a distribution, depending on the data that needs to be analyzed and what we want to explain to the audience. The wrong measurement of central tendency could misrepresent the data and distort it systematically.

Variability displays how scores differ, distribute or spread from one another. For example, if we have the same number, then there is zero variation. If the number keeps on repeating then there would be less variable (ex. 3,4,4,5,4).
Just like the central tendency, there are three measures of variability: range, standard deviation and the variance.

Range is …show more content…

As the sample size increases, there would be less difference between the biased (using n) and the unbiased (n-1) estimates of the standard deviation.

Here is an example, if n=10 and my numerator of the SD= 900, then
Biased estimate = 9.48 unbiased estimate = 10
Now, n= 10000, then
Biased estimate= 0.30 unbiased estimate= 0.300015
The difference is less as the sample size increased.

Variability is best seen when using a visual aid. Earlier, I mentioned about normal distribution and plotting the values would make it easier to see, whether it is normal or not.

It is not a perfect symmetry, but you could easily see the shape of the curve. The shaded area represents a total of 68% (34% on each side of the mean) of the price sold between $7.54 and $18.06. This is considered as a normal or bell shape distribution and there is no kurtosis or skewed.

Skewed is present when the curve has a one side tail and in the absence of symmetry. Kurtosis is seen in a flat or a peak distribution (Salkind, 2004,

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