Chapter 3 Flashcards
What is the mean?
the average of the data values, sum of data values/quantity of data values
pg. 49
What is the median?
the middle data value of a data set, if there are two find the average
when you cross out on either side
pg. 52
What is the mode?
the date value that is most common/repetitious, if more than one list them all, if none write ‘no mode’
pg. 52
What is the midrange?
exactly halfway between the highest and lowerst data values, low+high/2=midrange
pg. 53
What is the range?
the high data value-low data value in a varied data set
similar to midrange
pg. 63
What is the equation for sample stardard deviation?
s=,/E(x-X)^2/n-1
s=square root of the sum of (x-xbar)squared/n-1
n-1b/c sample is smaller
pg. 65
What is the sample variance?
s^2=E(x-X)^2/n-1
(S)squared=the sum of (x-xbar)squared/n-1
n-1 b/c sample is smaller
pg. 65
What is a standard deviation?
A measure of how spread-out the data is, big #=really spread out, small #=closer together
pg. 67
What is the equation for population standard deviation?
Q=,/E(x-U)^2/N
Q[sigma]=the square root of the sum of (x-U)[mu]squared/N
pg. 69
What is the equation for population variance?
Q^2=E(x-U)^2/N
Q[sigma]squared=the sum of (x-U)[mu]squared/N
pg. 70
What are symbols in population vs sample standard deviation and what do they mean?
Pop:Q(sigma) for SD of pop and U(mu) for mean of pop and N for pop size
Sample: S for SD of sample and X(xbar) for mean of sample and n for sample size
pg. 70
What is the equation for the range of usual values?
Min=U(mu)orX(bar)-2Q(sigma)orS
Max=U(mu)orX(bar)+2Q(sigma)orS
Max=mean+2timesSD
Min=mean-2timesSD
pg. 77
What is the range of usual values?
goes from the usual min to usual max; values between them are called usual values; values outside of the range of usual values are unusual
pg. 77
What are percentiles?
A value x is called the pth percentile of data set if p% of the data values are less than x; percentile means ‘percent below’
e.g. the 86th percentile mean that 86% are below 100-86=14% at or
pg. 85
What are quartiles?
Q1,Q2,Q3
the data is cut into 1/4 parts
Q2=median, Q1=lower, Q3=upper
found the same way as a median but if median is average(2 values) include them with Q1 and Q3
data values are odd don’t use median; data values are even use median
pg. 89
