Microcomputer Decision Support System
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Transportation Research Record 980 99 concern for the fiscal impact of transportation cessible to those whose responsibilities will not projects and a high degree of policy sensitivity to permit the luxury of becoming acquainted with com the level of employment and economic welfare in plicated run instructions or computer jargon. Michigan. The model accordingly provides a means of rapidly evaluating the income and fiscal effects of employment changes that are the outcomes or by products of transportation improvement projects. The Publication of this paper s ponsored by Conunittee on model is also quite easy to run and is therefore ac- Computer Graphics and Interactive Computing. Microcomputer Decision Support System F. MICHAEL TELLER and STUART L. MYERS ABSTRACT eration, and maintenance of various modes of trans portation. In addition, the department carries out various related licensing and administrative func In the past 2 years the Maryland Department tions. ot 'l'ransportation has developed a decision The department is supported by the Transportation support system that provides financial ad Trust Fund, which consists of revenues from motor vice to the Secretary of Transportation and fuel taxes, motor vehicle taxes, a portion of the to other policy-making officials within state corporation income tax, operating revenues Maryland state government. The components generated from MOOT-owned facilities, transit fares, and techniques used in developing this sys federal aid, and bonds and notes supported by the tem are described. To place the system in trust fund. perspective, there is a brief comparison of The Financial Planning and Analysis Section is the process before implementation of the part of the Secretary's staff. This section is s ystem with current practice. General guide charged with the responsibility for providing the lines are given to assist the reader in Secretary with impartial advice on the financial im identifying issues and criteria for develop pact of policy-level, program-level, and project ment of decision support systems. Thes e cri level decisions. teria are general in nature and may be ap plied to a wide variety of situations, not just financial planning or transportation related analysis. Conunents, conclusions, and MAJOR ISSUES specific hardware and software evaluations based on experience to date are offered. The Financial Planning and Analysis Section performs three distinct types of analyses. The first type of analysis is focused on providing revenue and expense forecasts covering 5-year and 20-year planning hori zons. The second major area of analysis is the de The purpose of this paper is to inform other profes termination of upper and lower limits of the depart sionals in the transportation field about the expe ment's bonding capacity given projected levels of riences of the Maryland Department of Transportation revenues, operating expenditures, and capital pro (MOOT) in developing and implementing a microcom gram spending. The final area of analysis deals with puter-based decision s upport system. In order that special projects and detailed analyses of a nonrou the reader may better appr eci ate the nature of work tine nature, performed by the Financial Planning and Analysis Before the department purchased a microcomputer Section at MOOT, a brief description of the depart and financial spreadsheet software package, these ment and its funding sources is included. In the analyses were perf ormed using a time- sharing service balance of the paper, concentration is on the com for the revenue project i ons and bonding capacity. ponents of the financial decision support system at Special projects were analyzed using hand-held cal MOOT, guidelines for developing a decision support culators, paper, and pencils, Each of these analyses system and financial modeling, and conclusions and required a substantial investment in time just to conunents regarding the MOOT experience to date. produce the initial results. Any sort of "what if?" or sensitivity analysis required a similar amount of time. BACK(;HUUNIJ lls on cxomplc of the amount of effort then re quired, the 5-year financial projection required MOOT is responsible for all state-owned transporta about l month to complete with the aid of the time tion facilities and programs. This responsibility sharing service and two mainframe computers. The includes the planning, financing, construction, op- output generated was a one-page report focused on a 100 Transportation Research Record 980 dozen or so key variables and linked to one national The current decision support system allows the economic forecast. Financial Planning and Analysis Section to p.oduce a Beginning with the purchase of the first micro greater quantity of work of higher quality than was computer in the fall of 1981, the Financial Planning possible previously. and Analysis Section refined the procedures and mechods used in their analyses. For example, the same 5-year projection now includes about 100 vari GUIDELINES FOR DEVELOPING A DECISION SUPPORT SYSTEM ables that are validated against four separate na tional economic forecasts. The MOOT 5-year financial The following list and the associated conunents projection now usually requires only l week from should assist in the development of a decision sup start to finish and is produced without any increase port system. Bear in mind that not all items will in the number of personnel in the Financial Planning apply to any specific situation and that possibly and Analysis Section. not all relevant considerations are included. The This dramatic increase in productivity has been a list is intended as a general guide to assist in result of the development of a decision support sys identifying the key elements required to develop an effective decision support system. tem based on a microcomputer and VisiCalc spread sheet software. A decision support system is an in 1. Determine the types of answers desired. Are teractive computer-based system that allows decision they one number, a range, or a conclusion? As an ex makers to analyze and solve complex, unstructured ample, the system used at MOOT for revenue and ex problems. Interactive is used to mean the abi lity to pense forecasts results in a single number for each directly enter any changes in the base model and to item for each year. On the other hand, special proj review results immediatel y. In t he fol lowi ng s ectio.n the components of the deci sion s upport system now ect analyses performed for the purpose of establish bei ng us ed a t MOOT by the Financial Planning and ing rates at s tate-owned facilities usually result Analys i s Section are d e sor i bed. in an acceptable- r a nge- type of answer . An example of where a conclusion-type answer is required is the analysis of past performance of specific units COMPONENTS OF THE DECISION SUPPORT SYSTEM within the organization. 2. Establish standards for acceptable levels of The first component of the decision support system error permitted for each of the various types of is a series of models used to project revenues and answers. For example, multiple-year forecasts may expenditures. By using the spreadsheet software a have an acceptable error of plus or minus millions number of techniques may be combined into a single of dollars. For analyses of past performance of spe model. For example, MOOT operating expenditures are cific units, the results generated should have a extrapolated from budget f i9u£es using an inflation minimal level of error because actual data are rate adjustment derived from national economic fore available. casts. For each year of the projection, the previous 3. Determine what types and amounts of data are year's expenditure is multiplied by the inflation required to develop and use the system. One key factor to derive the expense in that year. In addi question to be answered is whether the required data tion to this capability, certain variables within are available or can be acquired at a reasonable the forecast may be held constant from year to year. cost. Another technique used to make long-term projec-= 1. Dccum~nt all assumptions caused Uy lc:1ck of tions is regression analysis. Again, the spreadsheet information or unreliable information. package makes it possible to incorporate the regres 5. Determine how often the system will be used. sion coefficients into a formula to calculate re In general terms, the more frequently a support sys ceipts for a given year. tem is called on to generate a specific result, the To determine the department' s bonding capability, more detailed the required analysis becomes. De a model incorporating information about the depart tailed financial models require a longer setup time. ment's past bond issues, characteri stics of proposed 6. Standardize formats for the output gener issues, desired capita l progra m, and projected rev ated by each part of the system. Sununarizing the re enues was developed, This model was adapted from an sults of a quarterly forecast in the same format earlier linear progranuning model written in FORTRAN each time makes it easier for the decision maker to and run on a mainframe. The current model is much find needed information. quicker to revise and has the added advantage of 7. In financial analyses, graphs should be in allowing the user to immediately see the impact of cluded in the summary of results onl y as supporting changes in any of the input variables. information. Limit the number of graphs included in Models developed for special project analyses all the analysis to the bare minimum required to empha have a numl,.,, ur cuuuuun features. Wherever possible, size major points . However, graphic techniques can constants used within the models are referenced sep be extremely useful in assisting in the develop arately from outputs.