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DO NOW 01/29
The data set below corresponds to ages within the city of
Downtown Los Angeles:
26, 33, 35, 45, 27, 28, 29.
From this data set, find the mean and standard deviation.
WEIRD STUFF
NORMAL
DISTRIBUTIONS
AND INTERVALS
ENVIRONMENTAL STUDIES
Today we will…
Be able to describe what a normal distribution curve looks
like.
Understand how standard deviation relates to normal
distribution
STANDARD DEVIATION
REVISITED
We just learned about standard deviation
Today we will be discussing what a normal distribution curve is
and what it looks like. This is important because it allows us to
look at our data and determine whether or not it looks
“normal” or if it is “off”
NORMAL
DISTRIBUTION
NORMAL
DISTRIBUTION
This curve says that 68% of our data will fall within 1
standard deviation above and below.
95% 2 standard deviations above and below.
99.7% of data fall 3 standard dev above and below THE
MEAN.
This curve just tells us what values fall within the average. If
you’re within 1 standard deviation of the average, you are
considered normal within the distribution.
HEIGHTS AND ND
Red= average
Green= 68%
NORMAL
DISTRIBUTION
STANDARD DEVIATION
AND NORM. DIST.
Sample standard deviation can either increase or decrease
as a sample size gets larger.
If your standard deviation is large, that means your values
deviate largely from the mean.
That means that your results deviate significantly from the
mean of your sample, and thus are likely to not follow the
normal distribution pattern we would normally expect to see.
You want everything to be NORMAL!!!
EXIT TICKET
1. What does the bell curve below show? Elaborate on what
the standard deviations mean and the percentages. Give an
example(s).