1. Chapter 4 Topics –Sampling –Hard data –Workflow analysis –Archival documents

2. Sampling A process of systematically selecting representative elements of a population A System analyst has to make a decision on 2 key issues: –Which of the key documents and Web sites should be sampled –Which people should be interviewed or sent questionnaires

3. Need for Sampling The reasons systems analysts do sampling are –Reduction of costs More time & cost involves to ask all employees, reading all web pages Redundant data –Speeding up the data-gathering process Little burden to gather sampled data rather than all data –Improving effectiveness Ask detail questions to few employees which requires little time and the analyst can follow up on missing and incomplete data –Reduction of data-gathering bias i.e. Biased interview by the executive who like to see the project successful

4. Sampling Design Steps To design a good sample, a systems analyst needs to follow four steps: –Determining the data to be collected or described Identify attributes, variable, associated data item Data gathering methods like interview, questionnaire, observation etc. –Determining the population to be sampled Duration of analysis (i.e. 2 month, 1 year) Determine whether interview should take place on one level or all level of organization or outside of the organization –Choosing the type of sample –Deciding on the sample size

5. Four Types of Sampling Convenience samples –System analyst post a notice asking everyone interested in new sales performance report to come to a meeting at 1 PM on 12 th December –Easiest to arrange but most unreliable Purposive samples –Analyst chooses group of knowledgeable individuals who are interested in the field –Moderately reliable

6. Four Types of Sampling (contd.) Simple Random Sampling –Based on a numbered list of the population –Each person or document has an equal chance of being selected –Choose every k-th element –Not always practical Complex Random Sampling –Has three forms Systematic sampling: –select every k-th element like simple random sampling Stratified sampling: –sub group the population (i.e. executive level, line level) & then sample Cluster sampling: –select a group of document or people to study –There are many “sonali” bank around the country. Investigate 1 or 2 of them

7. Sample Size Sample size depends on the cost as well time required by the system analyst Sample size under ideal condition is determined by: –Sampling data on attributes –Sampling data on variables –Sampling qualitative data

8. Steps to Determine Sample Size for Attribute Data –Determine the attribute to sample –Locate the database or reports where the attribute is found –Examine the attribute and estimate p, the proportion of the population having the attribute –Make the subjective decision regarding the acceptable interval estimate, i –Choose the confidence level and look up the confidence coefficient (z value) in a table –Calculate σ p, the standard error of the proportion as follows: i σ p = z

9. p(1-p) n = + 1 σ p 2 Steps to Determine Sample Size for Attribute Data (Contd.) –Determine the necessary sample size, n, using the following formula:

10. Confidence Level Table

11. Hard Data In addition to sampling, investigation of hard data is another effective method for systems analysts to gather information Hard data can be obtained by –Analyzing quantitative documents such as records used for decision making –Performance reports –Records –Data capture forms –E-commerce and other transactions

12. Workflow Analysis Workflow analysis may reveal signs of larger problems, such as Data or information doesn’t flow as intended –Too many or too few people, wrong people receiving it Bottlenecks in the processing of forms Access to online forms is cumbersome –e.i. Web forms must be printed and then sent rather than electronic submission Unnecessary duplication of work occurs because employees are unaware that information is already in existence on another form that they don’t know Employees lack understanding about the interrelatedness of information flow –e.i. they don’t know that their output works as input to another person

13. Archival Documents A systems analyst may obtain some valuable information by abstracting data from archival documents Generally, archival documents are historical data, and they are prepared and kept by someone else for specific purposes