chapter 2 Flashcards
class width
(max # - max #) / # of classes
midpoint
(lower class + higher class) / 2
Relative frequency
class frequency / sample size
Σx
adding all the data enteries together
Σ
sigma
cumulative frequency
sum of that class and all previous classes
histogram
bars touch ( -0.5 from lower class and +0.5 from upper class)
frequency polygon
line graph that touches x-axis on both sides
Ogive
touches the x-axis on its first point; line graph
Stemplots
stem I leaf
stem
all the numbers except the last digit
ex: 34, 3 is the stem
leaf
last digit in the number
ex: 34, 4 is the leaf
trim the leaves
removing the last number
ex: 235 -> 2 (stem) I 3(leaf)
Pareto chart
bar graph with the largest number on the left -> smallest on the right
population mean symbol
μ
population mean equation
μ = Σn/n
sample mean symbol
x̄
sample mean equation
x̄ = Σx/n
position of the median
(n+1)/2
mode
highest frequency
mean of a frequency distribution
x̄ = (Σx times f)/n
mean frequency distribution explanation
n -> Σ(f)
x -> midpoints
f -> frequency
symmetric distribution
bell shaped
uniform
all equal
skewed left
tail on left
skewed right
tail on right
Variability
how spread out a group of data is
Range
highest number - lowest number
larger range = ______ variability
more
standard deviation
variation of the data from the mean
σ
standard deviation
population variance
σ^(2) = Σ(x-mean)^(2) / n
population standard deviation
σ = Square root of Σ(x-mean)^(2) / n-1
Sample variance
x̄^(2) = Σ(x-mean)^(2) / n
sample standard deviation
x̄ = Square root of Σ(x-mean)^(2) / n-1
empirical rule
68, 95, 99.7
Chebychev’s theorem
1 - 1/k^2
k is standard deviation
Coefficient variable
standard deviation of the data as a percentage of the mean
Coefficient variable equation
(standard deviation / mean) times 100
interquartile range (IQR)
Q3 - Q1
Outliers
- Less than Q1 - 1.5(IQR)
- Greater than Q3 + 1.5(IQR)
Percentile of x
(# of data less than x / total # of data) times 100
standardization formula
z score = (x-mean)/standard deviation
in calculator: standard deviation is ___
sx
in calculator: mean is ____
x̄
