Chapters 2-3
Decision Sciences 305 with Walden at University of Kansas
About this deck
By: Sarah Blaufuss
Created: 2010-02-17
Size: 34 flashcards
Views: 30
Created: 2010-02-17
Size: 34 flashcards
Views: 30
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.
“I have used this website for three exams, and I see a huge difference in my test results.”
Naj
Naj
Sign up (free) to study this.
a list or table containing the VALUES OF A VARIABLE and the CORRESPONDING FREQUENCIES with which each value occurs
frequency distribution
Why use frequency distributions?
- it's a way to summarize data
- it condenses the raw data into a more useful form
- allows for a quick visual interpretation of the data
type of data with a countable number of possible values
used to see how data is spread over different categories
used to see how data is spread over different categories
discrete data
proportion of total observations in a given category
frequency in category/ total # of observations
frequency in category/ total # of observations
Relative frequencey
running sum of relative frequencies
used to stratify customers/products
use to influence decisions (show what you want to show)
used to stratify customers/products
use to influence decisions (show what you want to show)
cumulative relative frequency
use to show trend lines or compare similar data
scatter diagrams and line charts
the arithmetic average of data values
mean
the most common measure of central tendency
mean
sum of values divided by the number of values
affected by extreme values (outliers)
affected by extreme values (outliers)
mean
in an ordered array, this is the "middle" number
NOT affected by extreme values
NOT affected by extreme values
median
sorted data
data array
the ith position
i=(1/2)n
i=(1/2)n
Median Index Point
Shape of distribution
mean<median
mean<median
left-skewed
shape of distribution
mean-=median
mean-=median
symmetric
shape of distribution
mean>median
mean>median
right-skewed
a measure of location
the value that occurs MOST OFTEN
not affected by extreme values
the value that occurs MOST OFTEN
not affected by extreme values
Mode
used when values are grouped by frequency or relative importance
weighted mean
total spread of data
range
scatter around the mean
sum of squares/(n-1)
sum of squares/(n-1)
Variance
most common use because same units as original sample
square root of sum of squares/(n-1)
square root of sum of squares/(n-1)
standard deviation
measures of this give information on the spread or variability of the data values
variation
compute difference between each value and the mean, square each difference and calculate sum
sum of squares
simplest measure of variation
difference between the largest and the smallest observations
=Xmax - Xmin
difference between the largest and the smallest observations
=Xmax - Xmin
Range
Disadvantage of the range:
ignores the way in which data are distributed
ratio of standard deviation to mean as expressed as %
used to measure variation relative to the mean
measures scatter in the data relative to the mean
used to measure variation relative to the mean
measures scatter in the data relative to the mean
Coefficient of variance
CV= pop. standard deviation/ pop. mean
Population coefficient of variation
CV=sample standard dev./ sample mean
sample coefficient of variance
z> or= +or- 3.0
outlier
the larger the Z score...
the greater the distance from the mean
z=(value-mean)/std dev
Z score
if the data distribution is bell-shaped, then the interval:
mean +or- 1 std dev contains about 68% of the values in the population or the sample
mean +or- 1 std dev contains about 68% of the values in the population or the sample
empirical rule
according to the empirical rule, if the data distribution is bell-shaped, then the interval of the mean +or- 1 std dev contains about this many of the values in the population or the sample
68%
according to the empirical rule, if the data distribution is
bell-shaped, then the interval of the mean +or- 2 std devs contains
about this many of the values in the population or the sample
95%
according to the empirical rule, if the data distribution is
bell-shaped, then the interval of the mean +or- 3 std devs contains
about this many of the values in the population or the sample
99.7%
About this deck
By: Sarah Blaufuss
Created: 2010-02-17
Size: 34 flashcards
Views: 30
Created: 2010-02-17
Size: 34 flashcards
Views: 30
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.
“I have used this website for three exams, and I see a huge difference in my test results.”
Naj
Naj