2.2 ONE QUANTITATIVE VARIABLE
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20 Terms
what is the notation for population mean?
MU - μ
represents the population mean (the average of an entire group).
why is bell shaped graph preferred?
It is a symmetrical graph that shows how data is spread out, with most values clustering near the average and fewer values at the extreme
what way does a right skewed graph go?
most values are on the left
what way does a left skewed graph go?
most values are on the right
what is the sample size notation?
the number of cases in the sample, is denoted as n
what are variable notations?
x & y
what is a mean?
the mean or average if the data values
what is the equation for mean?
Mean = sum of all data values/number of data values
what does the x - bar notation mean?
sample mean
what is range?
the range is the difference between the largest or maximum value and the smallest or minimum value
how do we find range?
subtract the biggest number (MAX) - smallest number (MIN)
what is standard deviation?
the standard deviation for a quantitative variable measure the spread of the sea
what is the notation for SAMPLE standard deviation?
s
what is the notation POPULATION standard deviation?
σ (“sigma”)
what is a z-score?
measures how far from the mean a data value is
the z score for a data value, x is
z = x-x(bar)/s (stand.dev.)
what else does the z-score provide?
is the # of standard deviations a value falls from the mean
puts values on a common scale w/ the center at 0 where values farther from 0 are more extreme
what is the 95% rule?
if a distribution of data approx. bell-shaped about 95% of the data should fall within 2 standard deviations of the mean ( And about 99.7% of the data should fall within 3 standard deviations of the mean!)
when is 95% applies in POPULATION?
95% of the data will be between…
mu - 2(sigma) and mu + 2(sigman
when is 95% applies in SAMPLE?
95% of the data will be between …
Xbar - 2 (standard deviation) & Xbar +2(standard deviation)
does the 95% rule apply to everything?
NO! only bell shaped graphs