Where researches gather data from whole populatin for a given measurement of interest
Sample
portion of the whole and if properly take, is rep of the whole
Descriptive Stats
business analyst is usin data gathered on a group to describe or reach conclusions about that same group.
Inferential Stats
researhers gather data from a sample and uses the stats generated to reach conclusion about the population from which the sample was taken
parameter
descriptive measure of the population.Greek letters
Nominal level
lowest level of measurement
representing nominal level data used to classify or categorize
Ordinal Level
measure is higher than nominal. RANK
Interval Level
measure next to the higest level of data in which the distancecs between consecutive numbers have meaning and the data are always numerical.
Ratio Level
highest level.
height, weight, time, volume
Parametric stats
require data to be interval or ration.
Nonparametric stats
analyze interval or ratio data.
Ungrouped Data
Raw data, or date that have not been summarized in any way
Grouped Data
data been organized into a frequency distribution.
Frequency Distribution
summary of data presented in the form of class intervals and frequencies.
Range
difference between the largest and smallest number
Class Midpoint
midpont of each class interval
halfway acoss the class interval and be calculated as the average of the class endpoints.
Relative Frequency
proportion of the total frequency that isw any given class interval in a frequency distribution.
Individul class frequency divided by the total frequency.
Cumulative frequency
a running total of grequencies through the classes of a frequency distribution.
Histogram
is a series of contiguous bars or rectangles that rep the frequency of data given class intervals.
Frequency Polygon
ploted as a dot at the class idpoint and the dots are connected by a series of line segments.
Ogive
cumulative frequency polygon
Dot Plot
display continuous , quatative data/
Steam and Leaf Plot
seperating the digits are the stem and consist of the higher value digits
Pie Chart
a circular depiction of data where the area of the whole pie represents 100% of the data and slices of the pie represent and a percentage breakdown of the sublevels.
Bargraph Bar chart
bars
Pareto Chart
use this tally to produce a vertical bar chart that displays the most common tyesps of defects, ranked in order of occurence from left to right.
scatter plot
two dimesional graph plot of pairs of points from numerical variables
measure of central tendency
yield info about the center, middle part or group of numbers
mode
the most frequently occuring value in a set
bimodal
the case of a tie for most frequently, occurring number.
multimodal
Data sets with more than two modes
arthimetic mean
the average of a groupe of numbersand is computed by summing all numbers and dividing the number of numbers.
measure of varaiablity
describe the spread of the dispersion of a set data.Using measures of varability in conjunction with measures of central tendency makes possible a more complete numerical description of the data
interquartile range
range of values between the first and third quartile.
q3-q1`
deviation from the mean
subtracting the mean from each value of data yields
mean absolute deviation
MAD
average of the absolute values of the deviations around the mean for a set numbers
Variance
average of the squared deviations about the arthmetic mean for a set of numbers.
sum of squares of x
sum of the squared deviations about the mean of a set of values
standard deviation
square root of variance
Two ways of applying standard deviation
Chebyshevs theorem
mean
is computed by summing the data values and dividing the number of values
Skewness
distribution is asymmetrical or lacks symmetry
Kurtosis
describe the amount of peakedness of a distribution.
Lepokurtic
distributions that are thin and high
Platykurtic
distributions that are flat and spread out
Mesokurtic
normal
box and whisker
diagram that utilizes the upper and lower quartiles along with the median and the two most extreme values to depict a distribution graphically.
A Priori
determined prior to the experiment
classical method of assigning probablities
a process that produces outcomes, and an event, which is an outcomes of an experiment.
relative frequency of occurence method
the probablity of an event occuring is equal to the number of times the ven has occurred in the past divided by the total number of opportunites for the event have occurred
subjective methold
assigning probality based onm the feelings inisghts determing the probablity
experiment
a process that produces outcomes
event
outcome of an experiment
elementary events
events that cannot be decomposed or broken down
intersection
contains the elements common to both sets
independent events
occurrence or nonoccurrence of one of the events does not affect the occurrence or nonoccurrence of the other event
complement
elementary events of an experiment not in A comprise its complement