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Business Statistics- Test 1
Ch. 1-5
115
Business
Undergraduate 3
02/09/2009

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Cards

Term
What is Statistics?
Definition

The art and science of collecting, analyzing, presenting, and interpreting data.

 

In business, it gives managers a better understanding of business enviroment, enabling them to make more informed and better desicions. 

Term

Data

 

 

 

Data Set

Definition

The facts and figures that are collected, analyzed and summarized for presentation and interpretation.

 

 

 

 

all the data collected in particular study

Term
Elements
Definition
The entities of which data are collected
Term
Variable
Definition
AN attribute or characteristic of an entity
Term
Observation
Definition

The set of measurements for a particular element

 

 

# is equal to # of elements

 

 

The number of measurments obtained for each element is queal to the number of varibles. 

 

total # of data items= # of observations multiplied by the # of variables. 

Term
What is the scale of measurement?
Definition

determines the amount of information contained in the data and indicates the data summarization and statistical analysis that are more appropriate.

 

 

Nominal

Ordinal

Interval

Ratio

Term
Nominal
Definition

data are labels or names

 

can be numeric or nonnumeric

 

 

Term
Ordinal
Definition

The data have the properties fo nomral data and cab be orderedin some meaningful way. RANKED

 

Ex. Survey: Excellent, Good, Poor

Term
Ratio
Definition

The data have the properties of interval data and contain an absolute zero value resutling in meaningful ratios.

 

 

Ex. Distance, Height, Weight, and Time

Term
Which Scales of Measurement describe Qualitative Data?
Definition
Nominal and Ordinal
Term
Which Scales of Measurement describe Quanitative Data?
Definition
Interval and Ratio
Term
What is Qualitative Data?
Definition
use labels or names to describe an attribute of an element
Term
Categorical Data can also be referred to as..
Definition
Qualitative Data
Term
What is Quantitative Data
Definition

It indicates how much or how many

 

it can be discrete or continuous.

Term
Why does the Statistical Method used for summarizing data depend on whether the data is qualitiative or quantitative
Definition

Qualitative variable is limited in terms of statistical analysis because its nominal. Its hard to do arthematic on the data.

 

Quantitative variables you are able to find the mean, median, mode, etc. as well as add, divide, mulitply, etc. 

Term
What is cross-sectional data?
Definition
Data that is collected at approximately the same time
Term
What is time series data?
Definition

Data that is collected over a period of time or series of time periods...

 

 

ex. Weather throughout the Year in San Diego

Term
Statistical Studies are classified as either..
Definition
Experimental or Observational
Term

 When a Statistical Study is Experimental.. the researchers...

Definition
control one or more independent varible (IV) to measure their influence on a dependent variable(DV)
Term
When a Statistical Study is Observational.. the researchers..
Definition

make no attempt to control the independent variable.

 

 

ex. survey for a restruant. 

Term
What are descriptive statitistics?
Definition
summaries of data that may be tabular, graphical, or numerical
Term
What is the most common numerical descriptive statistic?
Definition
average, or mean.
Term
What is the population?
Definition

The set of all elements of interest in a particular study.

 

 

 

Term
What is a Sample?
Definition
It is the subset of the population.
Term
What is a census?
Definition
the process of conducting a survey to collect data for the entire population.
Term
What is the process of conducting a survery to collect data for a sample called?
Definition
Sample Survey
Term
What is Statistical Inference?
Definition
The process of taking data from a sample and using it to make estimes and test hypotheses about the characteristics of a population.
Term
What are some unethical behavior for statistical practice?
Definition
  • improper sampling
  • inappropriate analysis of the data
  • Development of misleading graphs
  • use of inappropriate summary statistics
  • biased interpreation of the statisical results
  • multiple tests until a desired result is obtained

 

Term
you must always be ________ when conducting an experiment or you may have a bias on the interpretation of the statistical results.
Definition
impartial
Term
percent of statistics that are made up on the spot
Definition
67
Term
What are Sample Statistics?
Definition
numerical measures computed from a sample (eg. the sample mean, and the sample standard deviation
Term
What are the population parameters?
Definition
Numerical measures computed from a population (eg. the population mean, and the population standard deviation)
Term
What is the point estimate in Statistical Inference?
Definition
The sample statistic used to estimate the corresponding population parameter (eg. the sample mean is often used as a point estimate of the population mean)
Term
What is the Mean?
Definition

arithmetic average or average value of a variable

 

 

** Most important measure of location**

 

 

add up the numbers and divide by the total number of participants. The data can be skewed with an outlier. 

Term
The Sample Mean is the _________ of the population mean
Definition
Point Estimator
Term
What is the Median?
Definition

The middle value when the data is sorted in ascending order.

 

 

To compute the median, sort the data in ascending order:

if n is odd, the median is the middle number

if n is even, the median is the average of the two middle numbers

Term
Which measure of location is resitant to outliers?
Definition
median
Term
What is Mode?
Definition

The value occurs at the greatest frequency.

 

 

** There is NO MODE if no number is repeated**

*There can also be MULTIPLE MODES**

(ex. 1,2,2,3,3,5) mode- 2&3

Term
If the bell curve is ________, the mean and median will equal eachother
Definition

symmetrical

Term
If the _______ and ________are equal to eachother, that does not mean that the _____________ is symmetrical.
Definition

(1)mean (2)median (3)bellshape curve

Term
Bimodal
Definition
if a set of data has 2 modes
Term
multimodal
Definition
if a set of data has 3 or more modes
Term
What measure of location used as the most important in qualitative data
Definition

Mode

 

 

ex. distribution of soft drinks.

 

Want to know which soft drink is purchased most frequently.. Coke Classic

Term
What is a Percentile?
Definition

the pth percentile is a value that at least p percent of the observations are ≤to this value and at least (1-p) percent of the observations are ≥ to this value

 

 

ex. 67 percentile

67 percent fall below this percentile while 33 percent are above this percentile. 

Term
how do you calculate the pth percentile?
Definition

1. sort data in ascending order (small to large)

2. compute an index- i

i= (p/100)n

 

*p= percentile of interest, n=# of observations/times, i= the item which is in the P percetile

 

3. (a) if i is not an interger, round up.the next interger greater than i denotes the position of the pth percentile. 

(b) if i is an interger, the pth percentile is the average of the values in positions i and i+1

 

 

Term
The 50th percentile is also known as the...
Definition
median
Term
What are quartiles?
Definition
Specific percentiles, seperated in 4. 25,50,75
Term
What are the division points of Q1, Q2, and Q3?
Definition

Q1= first quartile, or 25th percentile

Q2= second quartile, or 50th percentile (median)

Q3= third quartile, or 75th percentile

Term
What are the measures of variabilty?
Definition
range, interquartile range, variance, standard deviation, coeffecicent of variation (cv)
Term
What is the simplist measure of variability?
Definition
range
Term
how do you calculate range?
Definition
largest value- smallest value
Term
How do you computer the Interquartile Range, and what is it?
Definition

IQR=Q3-Q1

 

Its the range for the middle 50% of the data.

 

It overcomes the dependency on extreme values

 

 

Term
What is Variance?
Definition

measure of variabiltiy that utizles all the data.

 

its the difference between the value of each observation (xi) and the mean

Term
What is the difference between each observation(xi) and the mean called?
Definition
deviation about the mean
Term
The __________ is useful in comparing the variabiltiy of two or more variables
Definition
variability
Term
For any data set, the sum of the deviations about the mean will...
Definition
always be zero
Term
The sample standard deviation is the ______________ of the population variance.
Definition
 point estimator
Term
What is the Coefficient of Variation?
Definition
its a relative measure of variability; it measures the standard deviation relative to the mean.
Term
The coefficent of variation is a useful statistic for comparing the variabiltiy of variables that have...
Definition
different standard deviations and different means
Term
Use the _______ and the _________ together, we can learn about the relative location of observations in a data set.
Definition
mean and standard deviation
Term
When data is skewed, you want to use the
Definition
median
Term
The _________ is resitant to outliers.
Definition
median
Term
the _____________ represents a more accurate number of the population.
Definition
median
Term
What is a Z-Score?
Definition

often reffered to as the standardized value. it is a number of standard deviations an observation is away from the mean. it tells you the location.

 

 

Term
Z scores should normally be used only in ____________ distributions
Definition

normal

 

 

exception: can sometimes be used in similar distributions

Term

(1)If Z score is positive, its ______ the mean

 

(2)If Z score is negative, its ______ the mean

Definition

(1) above

(2) below

Term
What are the distributions within the empirical rule?
Definition

µ±1σ(STD DEV)≈68%

µ±2σ(STD DEV)≈95%

µ±3σ(STD DEV)≈99.7%

Term
you can use ___________ to identify outliers.
Definition
Z-scores
Term
a data value is an outlier if it is ________ from the mean.
Definition
above ±3 STD DEV
Term
What is in a 5 number summary?
Definition

1. Smallest Value

2. First Quartile (Q1)

3. Median (Q2)

4. Third Quartile (Q3)

5. Largest Value

Term
A _________________ is a graphical summary of data that is based on a five-number summary.
Definition
box-plot
Term
What is Covariance?
Definition
it describes the linear association between two or more variables.
Term
What is the correlation coefficient?
Definition
The correlation tells us the relationship between the two variables. it further develops covariance.
Term

If the Correlation Coefficient is _________, the variables go in the same direction.  

 

/

 

If the Correlation Coefficient is _____________, the variables go in the opposite direction. 

 

\

Definition

positive

 

 

negative

Term
if the correlation coefficient is approx. 0, x and y are....
Definition
not linearly related.
Term
Weighted Mean
Definition
the mean is comuted by giving each observation a weight that reflects its importance.
Term
What is Variance?
Definition
a measure of variability based on the squared deviation of the data values about the mean.
Term

What is the experimental outcome when you...

 

 

Toss a Coin

Select a part for inspection

conduct a sales call

roll a die

play a football game

Definition

 

 

heads/tails

defective/nondefective

purchase/ no purchase

1,2,3,4,5,6

win, lose, tie

Term
What is probability?
Definition

 

 

its a numerical measure of the likelhood that an event will occur

Term
Probability values are always assigned on a scale from _____to______
Definition
0 to 1
Term
A probability near zero indicates an event is ____________ to occur
Definition
 unlikely
Term
A probability near 1 indicates an event is ________________ to occur
Definition
almost certain
Term
in probability, what is an experiment?
Definition
its a process that generates well-defined outcomes
Term

on any single repeitition of an experiment, how many possible experimental outcomes will occur?

 

 

(in reference to probability)

Definition
one and only one.
Term
what is the sample space for an experiment?
Definition
the set of all experimental outcomes. 
Term
experimental outcomes are also called...
Definition
sample points
Term
What is the counting rule for Multiple- Step Experiements?
Definition

if an experiment can be described as a sequence of k steps with n1 possibile outcomes on the first step, n2 possible outcomes on the second stpeh, and so on, then the total number of experimental outcomes is given by (n1)(n2)...(nk).

 

ex. tossing 2 coins. what are the possible outcomes?

n1=2; n2=2, so (2)(2)=4.

Term
In the Counting Rule for Combinations, order (does/doesnt) matter?
Definition
doesnt
Term

in a combination

 

0! = ?

Definition

 

 

 

1

Term

 

 

 

 

 

5! is equal to..

Definition

 

 

 

 

(5)(4)(3)(2)(1)= 120

Term
In the Counting Rule for Permutations, order (does/doesnt) matter?
Definition

 

 

DOES

Term

The three approaches most frequently used to assign probabilties are:

 

Definition

 

 

1. Classical

2. Relative Frequency

3. subjective methods

 

top 2 are the best approaches*

Term
The _____________method of assigning probabilities is appropriate when all the experimental outcomes are equally likely.
Definition

 

 

classical

Term

 

 

1

n

 

is used in the ________method

 

n being the experimental outcomes

Definition

 

 

 

classical

Term
The ____________________method of assigning probabilites is appropriate when data are available to estimate the proportion of the time the experimental outcome will occur if the experiment is repeated a large number of times.
Definition

 

 

relative frequency 

Term
The ______________method of assigning probabilties is most appropriate when one cannot realistically assume that the experimental outcomes are equally likely and when little relevant data are available.
Definition

 

 

subjective method. 

 

 

*its arbitrary, its a feeling, there isnt hard data, its pretty common espeically when data is hard to obtain. 

Term

For an experiment to be assigned probabilties it must:

 

 

(2 things)

 

Definition

 

 

1. the outcome must be between 0 and 1.

2. the sum of the probabilties for all the experimental outcomes must equal 1. 

Term

 

 

what is an event?

 

 

(probability, ch.4)

Definition

 

 

is a collection of sample points or experimental outcomes.

Term

 

What is the probability of an event?

Definition

 

 

It is equal to the sum of the probabilities of the sample points in the event. 

Term

 

Given an event A, What is the complement A?

Definition

 

 

its the event consisting of all sample points that are not in A. The completment of A is denoted by Ac

Term

 

 

 

P(A)+ P(Ac)=

Definition

 

 

 

 

1

Term

 

 

The _________ of A and B is the event containing all sample points belonging to A or B or both. It is denoted by ________.

Definition

 

 

 

union

 

 

 

A υ B

Term

 

 

Given two events, A and B, the _____________ of A and B is the event containing the sample points belonging to both A and B.  Its denoted by ________

Definition

 

 

intersection

 

A ∩ B

Term

 

What is the Addition law?

Definition

 

it is used to compute the probability of the union of two events.

 

 

P(AUB)= P(A)+P(B)-P(A∩B)

Term

 

What are Mutually Exclusive Events?

Definition

 

 

Two events are said to be Mutually Exclusive if the events have no sample points in common. 

Term

 

What is the Addition Law for Mutually Exclusive Events?

Definition

 

 

P(AUB)= P(A)+P(B)

Term

 

 

P(A∩B)= 0 when A & B are ___________.

Definition

 

 

mututally exclusive (disjoint)

Term

 

 

P(A|B) reads:

Definition

 

 

The probability of A given B

Term

 

 

What is Conditional Probability?

Definition

 

 

The probabulity of an event given that another event already occurred.

 

The conditional probability of A given B is P(A|B)= P(A∩B)/P(B)

Term

 

 

What is Joint Probability?

Definition

 

 

THe probability of two events both occurring; that is, the probability of the intersection of two events.

Term

 

What is Marginal Probability?

Definition

 

 

The values in the margins of a joint probability table that provide the probabilities of each event separately. 

Term

 

What are independent events?

Definition

 

 

two events A and B where P(A|B)=P(A)

or P(B|A)=P(B);

 

 

that is, the events have no influence on each other. 

Term

 

What is the Multiplication Law?

Definition

 

 

A probability law used to compute the probabilty of the intersection of two events.

 

For Dependent events: P(A∩B)= P(B)P(A|B) or  P(A∩B)= P(A)P(B|A).

 

For Independent events:P(A∩B)= P(A)P(B)

Term
Interval
Definition
The data have the properties of ordinal data and equal distances on the scale represent equal distances being measured.

*always numeric
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