Oral history the method of interviewing people in order to record and analyze past events. In this method the eyewitness of a past event narrate the event based on their memory. The historic record is preserved so that it can be later used by other historians 
- A research goal is identified to determine the result of the interview
- Background information is collected and Interviewee is identified. The interviewee is given details about the research goal and consult for the interview is obtained
- A questionnaire is prepared.
- The interviewer asks questions and the interviewee responds by giving details of the events.
- The entire conversation is recorded. The interview is transcribed and analyzed later.
Devices such as phonograph cylinders, acetate disc were used to record before the invention of audio tapes. In 1930 oral history of the American civil war, slavery was collected by the Works Progress Administration (WPA) 
- Oral history can be a valuable source to understand a historical period.
- It is used to study culture and study how individuals contribute to culture
- Oral history has been used to study social groups such as women, Latinos and African-Americans 
Knowledge of the previous generation is preserved. Enhances our understanding of past events
Oral history relies on the memory which may not be accurate. Interview of dead people is not possible  The eyewitness may narrate the event from his or her perspective which may have biases.
Examples in Informatics
Oral history was used to identify types of Unintended Consequences Related to Computerized Provider Order Entry - Journal of the American Medical Informatics Association Volume 13, Issue 5, September-October 2006, Pages 547-556
Cost Benefit Analysis
Cost Benefit Analysis is defined as weighing the total expected costs against the total expected benefits of one or more actions in order to choose the best or most profitable option. In health care cost benefit studies involves comparing the expenditure of resources for a specific intervention with the financial benefits gained from the treatment. Cost is generally ongoing or one time cost. The benefits are received over a period of time. This period of time is called payback period. Discount rate is added to the present value in order to evaluate future value. Cost benefit analysis is also used along with willingness of pay to make a decision
Jules Dupuit, a french engineer and Alfred Marshall a British economist are the pioneers of CBA  Benefit-cost methods were introduced in the U.S. by the U.S. Army Corp of Engineers.
- This is an important tool in medical decision making and used when there is a shortage of resources.
When introducing a new drug , the cost and benefits are analyzed
Used to choose among a range of alternatives, to make comparable projects of differing lengths, and to identify instances where costs and benefits place identifiable groups at special advantage or disadvantage 
Assigning monetary value for intangible factors such as life of a person is highly controversial and difficult to calculate Discount rate may not accurately define the future value Risks and uncertainties are difficult to predicate
Examples in Informatics==
A Cost-Benefit Analysis of Electronic Medical Records in Primary Care Department of Information Systems, Partners HealthCare System, Boston, Massachusetts 02481, USA.