QBA Chapters 3 Review Final
what will the sum of all of the distance data from the means going to equal?
0. every-time. guaranteed.
What are the properties of the median?
1. does not use all of the data values in its calculations 2. it is not affected by a skewed distribution
what are the properties of the mean?
1. most widely used measure of central location 2. all values are used in its calculations 3. mean is affected by a skewed distributions (IT GETS PULLED THE DIRECTION OF THE -extreme data values- or SKEW) 4. mean is a balance point for a set of data
how do you find the median?
1. put the data into order 2. find the location of the median-------- n+1/2
how do you calculate the iqr?
3rd quartile- 1st quartile
The range of a set of numbers is approximately equal to how many standard deviations?
6
what is the chebychev theorem for xbar+2s
75%
what is the chebychev theorem for xbar+3s
89%
What is chebychevs theorem useful for?
ANY distribution
Which rule works with any distribution?
Chebychevs
what is the numerical summary that is appropriate for qualitative data?
ONLY the mode
what is a weighted mean?
When not all the values are of the same influence to the calculation
what is the distance from the mean formula?
Xi-xbar
what is the relationship between the mean and the mode and the median on a symmetrical graph?
all equal to each other
arithmetic mean=
average mean
why is chebychev conservative?
because it works for every deviation measure
is chebychev theorem conservative or liberal?
conservative
How do you read a box plot?
data within the fences are moderate outliers. Data values outside of the fences are extreme outliers.
what are the properties of the range?
it is highly affected by extreme values, it only looks at two data values (this is its weakness)
When it says xbar with a subscript w
it means a weighted mean
what is the relationship between the mean, mode, and median, on a skewed left graph.
mean is the smallest, median the middle, and mode the highest (only difference between skewed right and left is the direction)
what is standard deviation?
measures the "typical" dispersion of a set of data around its mean.
what is the interquartile range?
measures the spread/range of the middle 50% of the data -throws out tails
what is the relationship between the mean, mode, and median on a skewed right graph
mode is the highest, median in the middle, mean the lowest (only difference between skewed right and left is the direction)
what is the chebychev theorem for xbar+1s
none its not there
is the mean the middle?
not necessarily
big N =
population
you use the (average mean) if you are dealing with a _______ data set
population
What is variance?
reflects the dispersion of all the data values around the mean of those values.
little n=
sample
Quartiles
special percentiles that split the data into quarters
The value showing how spread out from the mean it is, is the
standard deviation value
what is the formula for weighted means
sum of W(x) divided by sum of W
population mean formula:
sum of x values /N
what is the sample mean formula?
sum of x values/n
how do you find the median with an even n
take the average of the two values around the 1/2 number. ) (avg the 5th and 6th numbers together)
what is the median?
the center of a set of data
Which rule is used with symmetrical distribution?
the empirical rule
What is the mode
the most frequently occurring value
What is the range
the overal span. ***the biggest number minus the smallest number***
what is the "average of squared deviations?"
the population variance
what is chebychevs theorem
the proportion of observations that lie within K standard deviations of the mean is at least (1-1/k^2) if K is bigger than 1
S.D. is in what kind of units?
the same as the original data
what unit is variance in?
units squared
what is the sign for sample mean
x bar
What is the empirical rule?
xbar plus or minus 1s= 68% plus or minus 2s=95% plus or minus 3s=99.7%
if your numbers are: 1,2,3,4,5,6,300, will your mean be skewed?
yes, because your numbers are going to be affected by the extreme outlier 300.
if there is a tie, what is the mode?
you just list both