Measures of average are also called measures of central tendency. Their purpose is to provide a numerical figure which may describe the level of entire distribution. For example let five students be awarded marks as follows. 10, 11,9,12 and 13.All these scores are different from each other but at least there is one such score to which the rest of the scores standby or nearby. There are three measures of central tendency as follows; mean, median and mode (Srivastava et al., 1989). These are used at different occasions when making a decision for example when the administration of the state is requiring to collect and analyze data related to population and material wealth of the country for the purpose of planning and finance.
Mean can be used when making the instructional decisions. This can be used by a teacher to get the knowledge about the student’s entry behavior and background; in this case the distribution should be normal meaning all the scores should be present. By getting the mean of the student’s scores, the teacher will be able to identify the teaching technique to use according to their strengths and weaknesses. Consequently, the mean should be used when the teacher is evaluating the degree to which the objectives have to be achieved so that he/she will be able to encourage good study behavior among the students. Incase the scores are scattered the mean must be used so that all the scores are brought together to enable decision making to take place may be about the performance.
Median should be used for guidance decisions. Students should be guided in their vocational choices; educational performance and their personal problems therefore median can be used to determine the average performer in class and can be advised accordingly. At the same time, median is used to make guidance decisions especially when a quick and easily computed measure is required to provide the data about significant characteristics which can help a certain group of people to understand themselves better.
Mode should be used in research decisions in the sense that for any research to be carried out there must be collecting of the data on the issue at hand. After collecting the data, scoring, and analysis should be done and interpretation of the whole information given. When the information is incomplete mode must be used. It is also used when one wants to know the fashion of the most recurring measure or score.