DATA ANALYTICS PRELIM

Data

The facts and figures collected, analyzed, and summarized for presentation and interpretation

Variable

A characteristic or a quantity of interest that can take on different values

Observation

Set of values corresponding to a set of variables

Variation

The difference in a variable measured over observations

Random variable / uncertain variable

A quantity whose values are not known with certainty

Population

All elements of interest

Sample

Subset of the population

Random sampling

A sampling method to gather a representative sample of the population data

Quantitative data

Data on which numeric and arithmetic operations, such as addition, subtraction, multiplication, and division, can be performed

Categorical data

Data on which arithmetic operations cannot be performed

Cross-sectional data

Data collected from several entities at the same, or approximately the same, point in time

Time series data

Data collected over several time periods

Experimental study

A variable of interest is first identified, then one or more other variables are identified and controlled or manipulated so that data can be obtained about how they influence the variable of interest

Nonexperimental study / observational study

Make no attempt to control the variables of interest

Strategic decisions

Involve higher-level issues concerned with the overall direction of the organization; define the organization's overall goals and aspirations for the future

Tactical decisions

Concern how the organization should achieve the goals and objectives set by its strategy; usually the responsibility of midlevel management

Operational decisions

Affect how the firm is run from day to day; domain of operations managers, who are closest to the customer

Business analytics

Scientific process of transforming data into insight for making better decisions

Descriptive analytics

Encompasses the set of techniques that describes what has happened in the past

Data query

A request for information with certain characteristics from a database

Data dashboards

Collections of tables, charts, maps, and summary statistics that are updated as new data become available

Predictive analytics

Consists of techniques that use models constructed from past data to predict the future or ascertain the impact of one variable on another

Data mining

Used to find patterns or relationships among elements of the data in a large database; often used in predictive analytics

Simulation

Involves the use of probability and statistics to construct a computer model to study the impact of uncertainty on a decision

Prescriptive analytics

Indicates a best course of action to take

Optimization models

Models that give the best decision subject to constraints of the situation

Simulation optimization

Combines the use of probability and statistics to model uncertainty with optimization techniques to find good decisions in highly complex and highly uncertain settings

Decision analysis

Used to develop an optimal strategy when a decision maker is faced with several decision alternatives and an uncertain set of future events; employs utility theory

Big data

A set of data that cannot be managed, processed, or analyzed with commonly available software in a reasonable amount of time

Accuracy

Data quality dimension asking: Does it match reality?

Completeness

Data quality dimension asking: Are required values present?

Consistency

Data quality dimension asking: Is one format used?

Validity

Data quality dimension asking: Does it follow rules?

Uniqueness

Data quality dimension asking: Is each record represented once?

Timeliness

Data quality dimension asking: Is it current enough?

Data cleaning

The process of detecting and correcting inaccurate, incomplete, inconsistent, duplicated, or irrelevant data to make the dataset reliable and analysis-ready

Data transformation

Changes structure or representation; prepares the structure for a purpose

Mean imputation

Missing-value action that uses the numerical center; used for symmetric numerical data

Median imputation

Missing-value action that is less affected by extreme values; used for skewed data or outliers

Mode imputation

Missing-value action that uses the most common/allowed label; used for categorical data

Outlier

A value that is unusually far from most values

Invalid value

A value that breaks defined data rules

Central tendency

Uses one value to describe the center or typical value

Mean

Central tendency measure that uses every observation; used when values are numerical and no extreme value strongly distorts the center

Median

Central tendency measure that uses ordered position; resistant to outliers; used when extreme values pull the mean or for ordinal data

Mode

Central tendency measure that uses frequency; answers what occurs most frequently; used for the most common value or category

Geometric mean

Best measure for growth rates because growth is multiplicative

Frequency distribution

A summary of data that shows the number (frequency) of observations in each of several nonoverlapping classes (bins)

Relative frequency distribution

Tabular summary of data showing the relative frequency for each bin

Percent frequency distribution

Summarizes the percent frequency of the data for each bin

Cumulative frequency distribution

Shows the number of data items with values less than or equal to the upper class limit of each class

Histogram

A common graphical presentation of quantitative data constructed by placing the variable of interest on the horizontal axis and the frequency measure on the vertical axis

Skewness

Lack of symmetry; an important characteristic of the shape of a distribution

=COUNTBLANK

Excel function used to count blanks

=TRIM

Excel function used to remove extra spaces

=PROPER

Excel function used to standardize capitalization/names

=UPPER

Excel function used to standardize codes to uppercase

=CLEAN

Excel function used to remove non-printable characters from imported text

=VALUE

Excel function used to convert a number stored as text into a numeric value

=DATEVALUE

Excel function used to convert date stored as text to an Excel date

=ISNUMBER

Excel function used to verify if a cell contains a real number

=IF

Excel function used for conditional flagging (e.g., flagging empty cells as "Missing")

=IFERROR

Excel function used to handle formula errors after investigation

=COUNTIFS

Excel function used to count values that fall within a valid range

=AVERAGE

Excel function used to calculate the mean

=MEDIAN

Excel function used to calculate the median

=MODE.SNGL

Excel function used to find the most common numeric value