Bài thuyết trình môn Phân tích & thiết kế hệ thống - Đề tài: Information gathering - Unobtrusive methods - Phạm Quang Minh
Information Gathering:
Unobtrusive Methods
2
Team 2
Pham Quang Minh – 1512016
Le Manh Hung – 1511343
Cao Van Quang – 1512630
Lecturer
Nguyen Thanh Tung
Major Topics
• Sampling
• Quantitative document analysis
• Qualitative document analysis
• Observation
• STROBE
• Applying STROBE
Kendall & Kendall
5-2
Sampling
• A process of systematically selecting
representative elements of a population
• Involves two key decisions:
• What to examine
• Which people to consider
Kendall & Kendall
5-3
Need for Sampling
The reasons systems analysts do
sampling are:
• Containing costs
• Speeding up the data gathering
• Improving effectiveness
• Reducing bias
Kendall & Kendall
5-4
Sampling Design
• To design a good sample, a systems
analyst must follow four steps:
• Determining the data to be collected or
described
• Determining the population to be sampled
• Choosing the type of sample
• Deciding on the sample size
Kendall & Kendall
5-5
Figure 5.1 Four main types of
samples the analyst has available
Kendall & Kendall
5-6
The Sample Size Decision
• Determine the attribute
• Locate the database or reports in which the
attribute can be found
• Examine the attribute. Estimate p
• Make the subjective decision regarding the
acceptable interval estimate i
• Choose the confidence level z
• Calculate the standard error sp
• Determine the sample size n
Kendall & Kendall
5-7
Figure 5.2 A table of area under a normal curve can
be used to look up a value once the systems analyst
decides on the confidence level
Kendall & Kendall
5-8
Calculate the Standard Error of
the Proportion
sp = i/z
i = interval estimate
z = confidence
coefficient found in
the confidence level
lookup table
Kendall & Kendall
5-9
Determine the Sample Size
p(1-p)
n =
+ 1
2
σp
σp = standard error
ρ = the proportion of the population having
the attribute
Kendall & Kendall
5-10
Example: A. Sembly Company
• Determine that you are looking for orders
with mistakes
• Locate order forms from the past six months
• Examine order forms and conclude that
p=5%
• Subjective decision of acceptable interval i =
± 0.02
• Look up confidence coefficient z-value = 1.96
• Calculate sp = i / z = 0.02/1.96 = 0.0102
• Determine n; n = 458
Kendall & Kendall
5-11
Investigation
• The act of discovery and analysis of
data
• Hard data
• Quantitative
• Qualitative
Kendall & Kendall
5-12
Analyzing Quantitative Documents
• Reports used for decision making
• Performance reports
• Records
• Data capture forms
• Ecommerce and other transactions
Kendall & Kendall
5-13
Reports Used for Decision Making
• Sales reports
• Production reports
• Summary reports
Kendall & Kendall
5-14
Figure 5.3 A performance report
showing improvement
Kendall & Kendall
5-15
Figure 5.4 A manually completed
payment record
Kendall & Kendall
5-16
Data Capture Forms
• Collect examples of all the forms in use
• Note the type of form
• Document the intended distribution
pattern
• Compare the intended distribution
pattern with who actually receives the
form
Kendall & Kendall
5-17
Figure 5.5 Questions to ask about official and
bootleg forms that are already filled out
Kendall & Kendall
5-18
Analyzing Qualitative
Documents
• Key or guiding metaphors
• Insiders vs. outsiders mentality
• What is considered good vs. evil
• Graphics, logos, and icons in common
areas or Web pages
• A sense of humor
Kendall & Kendall
5-19
Analyzing Qualitative
Documents
• Email messages and memos
• Signs or posters on bulletin boards
• Corporate Web sites
• Manuals
• Policy handbooks
Kendall & Kendall
5-20
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