#
Process Analysis for Abnormal Condition

The target of the process analysis for abnormal condition is
, for example,
"Why does the distribution happen?" and
"Why did the wrong product be made?".
Those are found in the
process analysis for normal condition
.

##
Before Starting Data Analysis

Before starting analysis of X, we should grasp what happened.
"What happened" is the information of Y.
The first step is studying Y, the second step is analyzing X.

For example, if the problem is the unknown matter in the products,
before looking for the machine of the cause,
I analyze the ingredients and the shape of the matter.
This information will be powerful hint.

Before the step of the process analysis, we need to collect information about the fact.
In many cases, we need much time.
The success of data analysis depends on these steps.

##
Visual Analysis

It is important to look at "Data" itself because the change of the style of the data may be the cause of abnormality.
The basic of
Data Science
is to look at data itself.

Graphs are useful to look at many numbers.

Using mathematical model is less important.
Without looking at data, mathematical approaches do not work well because actual data has complicated background.

##
Statistical Analysis

###
To Make Statistical Analysis Methods Useful

Mathematical models of
regression analysis
and
discriminant analysis
uses formulation and
normal distribution
.
This approach does not match for raw data in many cases.

We need
stratified sampling
or data cleansing to use this approach.

Data cleansing is often used to delete abnormal data.
But for the analysis of abnormality, using abnormal data may work well.
Deleting abnormal data is used to compare mathematical model of normal condition and abnormality.

###
Useful Methods to Analyze Abnormality

The idea of
Decision tree
is the key to analyze.
It divides samples.

MT method
can express abnormality as quantity data.

Statistical Way of Making Hypothesis

Outlier and Missing Value

Making Hypothesis

NEXT Cause analysis of temperature and humidity