LEARNING UNIT 1
Information gathering, strategies, methods
INFORMATION GATHERING STRATEGIES
A strategy should be evolved by the analyst to gather information. The
strategy consists of identifying information sources, evolving a method of
obtaining information from the identified sources and using an information
flow model of organization
INFORMATION SOURCES
The main sources of information are users of the system, forms and
documents used in the organization, procedure manuals, rule books etc,
reports used by the organization and existing computer programs(If Any).
INFORMATION GATHERING METHODS
Searching for information
Information can be gathered by interviewing top-level management, middle
level management and operational staff. Besides Interviews group
discussions also help the analyst to gather information. It is not possible to
obtain all information in a single interview, more than one interview is thus
required.
PLANNING AN INTERVIEW
Before starting the interview the analyst must make a list of people to be
interviewed and in what order, plan and note down a list of questions to be
asked, plan several interviews with same person-mainly to clarify doubts
and interview groups as appropriate.
INTERVIEWING TECHNIQUE
There are some guidelines to ensure a successful interview:
Make an prior appointment with the person to be interviewed and meet him
at the allotted time. Read background material and go prepared with the
checklist. State purpose of interview. Be punctual and pay attention to what
user says. Do not use computer jargon. Obtain both quantitative and
qualitative Information. Discriminate between essential and desirable
requirements. State what you understand and get it confirmed. Do not
prolong interview and summarize the information gathered by you during
the interview and verify this with the user
USE OF QUESTIONNAIRES
Questionnaires are useful for collecting statistical data. Sometimes the
questionnaires are not promptly replied and several follow-ups/personal
interviews may be required to get questionnaires back from respondents
But if the questionnaires are short the probability of getting the reply is high
When data has to be collected form large number of people questionnaires
are useful.
OTHER METHODS OF INFORMATION GATHERING
Other methods of information search are:
Systems used in other similar organization
Observe workflow in workplace
Repository of systems developed for similar organizations available.
LEARNING UNIT 2
System requirements specification, classification of
requirements as strategic, tactical, operational and statutory
SYSTEM REQUIREMENTS SPECIFICATION (SRS)
SRS is obtained after excessive discussions with the user.
System requirements specification specifies what Information requirements
will be provided. It does not specify how the system will be designed.
Developing SRS is most important and difficult task of a Systems analyst
How SRS is developed
Analyst examines the current system, finds out the shortcomings of the
system as seen by the user. He then develops an SRS which is
understandable by the user and which can be used for detailed design of the
system.
Ideal characteristics of SRS
Complete and Unambiguous.
Specifies operational, tactical, and strategic information requirements
Eliminates possible later disputes between users and Analyst
Uses Graphical aids understood by users who are not computer literate and
will also be useful in design.
Jargon Free.
DEVELOPING A DOCUMENT FLOW DIAGRAM
EXAMPLE WORD STATEMENT
“Our company receives many items from several vendors each accompanied
by a delivery note. A receiving office receives the item and checks the
delivery note with corresponding order. Any discrepancy is reported to
purchase office. The items received along with items received note (with
details of items) is sent to the inspection office.”
ENTITIES IDENTIFIED-Vendors, Receiving office, Inspection office
DOCUMENTS IDENTIFIED-Delivery note, discrepancy note, Items
Received note.
Using these a document flow diagram is drawn
The diagram is interpreted as follows:
1) Vendors deliver items to receiving office accompanied by a delivery note
2) Receiving Office sends items to inspection office along with an items
received note
3) Receiving office sends discrepancy note to Purchase office
ENTITIES: Vendor, Receiving office, Inspection office and purchase
office
DOCUMENTS: Delivery note, Items received note and discrepancy note
Vendor Receiving
Office
Inspection
office
Purchase
Office
Delivery note Items
Received
Discrepancy note
note
Delayed Items Delivered Items
Indicates Physical
flow of items
Indicates Documents
DATA FLOW DIAGRAM (DFD)
DFD has entities and data flows, DFD specifies processing performed by
some of the entities. It specifies which entities generate documents and also
indicate their flow. Data stores which are referred while processing data and
in which processed data may be written or stored are also represented in the
Diagram
•Entities are, originators of data and “consumers” of data
•Vendor, Inspection office and purchase office are entities in the above
diagram
•Data flows are delivery note, items received note and discrepancy note
•A circle is used to depict a process
•A pair of parallel lines depict a store
Vendor
Receiving
Process
Inspection
Office
Purchase
Office
Orders
Delivery
note
Items
Received
note
Discrepancy
note
Data elements in the data flow:
Delivery note:
Order no,Vendor code,Vendor name and address,Item name, Item
code,Delivery date,Quantity supplied,units.
Items Received note:
Order no,Item name,Item code,Delivery date,quantity,supplied,units.
Discrepancy note:
Order no,Vendor code,Vendor name and address,Item name, Item
code,Order date, Delivery date,quantity supplied,units, excess/deficiency,No
of days late/early.
Receiving office order file
Order no,Order date,Item name,Item code,Vendor code,Vendor Name and
address,Quantity ordered,delivery period.
PROCESSING RULE
The statements given below are shown to the user for his approval.
English statement
1.Compare order no in delivery note with that in order file. If no match
return item to vendor.
2.If order no matches then compare item codes, if no match return item to
the vendor.
3. If order number matches compare qty delivered with quantity ordered. If
excess or deficient send discrepancy note to purchase office.
4. If order number matches compare date of delivery with expected date. If
late or early send discrepancy note to purchase office.
5.In case3 and case4 send items received note to inspection office
MODULARIZING REQUIREMENTS SPECIFICATIONS
SRS Document now consists of Document flow diagrams(as many as
needed), Data Flow Diagrams, Data elements of each data flow and Data
store, processing rules carried out in each circle of DFD, a descriptive
statement of operational,tactical,strategic information will be provided,
a data dictionary which consolidates all data elements in the document and
data store.
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