Data Stratification
Prepared By: Vaibhav C.Gandhi Guided By: Pinesh A.Darji
Professor
M.E.C.E. 3rdsem PIET
PIET
Tools to collect and analyze data
Check sheet: A generic tool that can be
adapted for a wide variety of purposes, the
check sheet is a structured, prepared form for
collecting and analysing data.
Control chart: A graph used to study how a
process changes over time.
Histogram: The most commonly used graph
for showing frequency distributions, or how
often each different value in a set of data
occurs.
Conti..
Scatter diagram: A diagram that graphs
pairs of numerical data, one variable on
each axis, to look for a relationship.
Survey: Data collected from targeted
groups of people about their opinions,
behaviour or knowledge.
What is Stratification?
Stratification is a technique used in
combination with other data analysis tools.
When data from a variety of sources or
categories have been lumped together, the
meaning of the data can be impossible to
see. This technique separates the data so that
patterns can be seen.
Stratification is the process of dividing
members of the population into
homogeneous subgroups before sampling.
When to use Stratification?
Before collecting data.
When data come from several sources or
conditions, such as shifts, days of the
week, suppliers or population groups.
When data analysis may require
separating different sources or conditions.
Data stratification helps the auditor, in
order to perform tasks
Sample planning
Audit Planning
Reasonableness tests
Identification of potential exceptions
Determining if “outliers” may exist
Obtaining a better understanding of the
population
Comparison of two components of one
population
Stratification Procedure
Before collecting data, consider which
information about the sources of the data might
have an effect on the results. Set up the data
collection so that you collect that information as
well.
When plotting or graphing the collected data on
a scatter diagram, control chart, histogram or
other analysis tool, use different marks or
colours to distinguish data from various sources.
Analyse the subsets of stratified data separately.
Example
The ZZ-400 manufacturing team drew a
scatter diagram to test whether product
purity and iron contamination were related,
but the plot did not demonstrate a
relationship.
Then a team member realized that the data
came from three different reactors. The
team member redrew the diagram, using a
different symbol for each reactor’s data.
Result
• The data from reactor 2 and reactor 3 are
circled. Even without doing any
calculations, it is clear that for those two
reactors, purity decreases as iron
increases. However, the data from reactor
1, the solid dots that are not circled, do
not show that relationship. Something is
different about reactor 1.
Numeric data stratification
The data stratification procedure classifies
numeric amounts into “buckets” or value
ranges specified by the auditor. The
purpose is to classify numeric amounts in
order to determine the most frequently
occurring values, largest and smallest
values, etc.
Example: 1
using the “stratify” form, obtain frequencies
and totals for invoices classified into various
numeric ranges.
Form values:
File: C:\Program Files (x86)\EZS\AC\data\fa.xls
Sheet: FA$
Numeric col: cost
Strata: -100 0 100 200 300 500 1000 2000 3000 4000 5000 6000
Chart : Reasonableness testing
Report: Audit planning
Example : 2 with condition
Chart: Reasonableness Testing
Report : Audit planning
Thank You.. !!
