Business Statistics

Descriptive Statistics -

methods that primarily assist summarize and present data

Inferential Statistics -

methods that use data from a small group to reach conclusions about a larger group

Variable:

a characteristic or property of an item or individual

Data:

the set values associated with one or more variables

Population:

contains all the items or individuals of interest that you seek to study

Sample:

contains only a portion of a population of interest

Statistic:

value that summarizes the data of a particular variable for a sample

Parameter:

summarizes the value of a specific variable for a population

Nominal Scales:

classifies data into distinct categories in which no ranking is implied

Ordinal Scale:

inversely the ranking is implied here.. think of school - freshman, sophomore, junior, senior - this and nominal scales both fall under the umbrella of categorical

Discrete:

concrete number.. a counting process is involved.. this is classified as numerical (quantitative)

Continuous:

something that can vary over time.. variables arise from a measuring process

Meanings (interval scale) -

the difference in measurements is meaningful in quantity but has no true zero point

(Ratio scale) -

same as interval scale however this in fact does have a true zero point

Judgement:

you gather opinions of preselected experts on the subject matter

Convenience:

selected basely on the fact that its either easy, inexpensive, convenient.

Simple Random

Every individual or item has an equal chance of being chose.

Systematic:

sampling method where you pick a random starting point in the population list, then select every kth individual from there, with k being the population size divided by the desired sample size.

Stratified:

A probability sampling method where the population is divided into distinct subgroups and a random sample is drawn from each, so every subgroup is represented proportionally.

Cluster:

A probability sampling method where you randomly select entire groups (?) rather than individuals, then collect data from within those groups.

stacked data -

creation of a single column for the variable of interest and create additional columns for the potential grouping variables

unstacked data -

create separate numerical variables for different groups

Summary Table:

tallies the frequencies or percentages of items in a set of categories so that you can see differences between categories

Contingency Table:

used to study patterns that may exist between the responses of two or more categorical variables

Ordered Array

An (?) is a sequence of data, in rank order, from the smallest value to the largest value.

Frequency Distribution

The ___ is a summary table in which the data are arranged into numerically ordered classes.

Scatter plots

(?) are used for numerical data consisting of paired observations taken from two numerical variables.

Time-Series Plot

A ___ is used to study patterns in the values of a numeric variable over time.

Simple Event:

An event described by a single characteristic. The probability of a ___ is called simple probability.

"OR" Event:

An outcome is in the event A (?) B if the outcome is in A or is in B or is in both A and B. The event A OR B can also be written as A Union B, with notation 𝐴 ∪ 𝐵.

"AND" Event:

An outcome is in the event A (?) B if the outcome is in both A and B at the same time, which is also called Joint Event. The event A AND B can also be written as A Intersection B, with notation 𝐴 ∩ 𝐵

Complement of event

The ___ A is denoted A′ (read "A prime"). A′ consists of all outcomes that are NOT in A.

Conditional probability

The ___ of A given B is written P(A|B). P(A|B) is the probability that event A will occur given that the event B has already occurred.

Independent:

Two events A and B are (?) if the knowledge that one occurred does not affect the chance the other occurs.

Mutually exclusive events:

Events that cannot occur simultaneously.

Sample Space

The ___ of an experiment is the set of all possible outcomes.

Outcome

A result of an experiment is called (?)

Experiment

An ___ is a planned operation carried out under controlled conditions.

Chance Experiment

If the result is not predetermined, then the experiment is said to be a (?)

P(A) = 0

event A can never happen - event A is an Impossible Event.

P(A) = 1

event A always happens - event A is a Certain Event.

P(A) = 0.5

event A is equally likely to occur or not to occur