[qdeck ” bold_text=”false”]
[h]SL 4.9 normal distribution
[q] Normal distribution
[a] Normal distribution refers to a situation where we have a large set of one-variable data. It is a data set that is mostly centered around the mean, in a symmetrical manner. As it is continuous data, showing probabilities in a bar chart wouldn’t work, and instead, a smooth line is required, in the shape of a bell curve. The total sum of probability is still 1, but here, that means the area under the curve = 1.
[q] Spread
[a] If the mean (μ) decides the central location, then the standard dev. (σ) decides how spread out the data is.
[q] Finding Probability/Area
[a] If you tell your GDC the μ and σ, then you can ask what percentage of the population lies between certain values. This is the same as asking for the probability of somebody chosen at random being in that interval, OR, the area under the curve between that interval. This process is called ‘normal cdf‘ on your GDC.
[q] Finding missing boundaries
[a] A GDC can also find an upper boundary, given the area/ probability below, and μ and σ. If you are asked about a lower bound, you must do 1-area to effectively turn it into an upper bound.
[x] Exit text
(enter text or “Add Media”; select text to format)
[/qdeck]