CONSIDERATIONS IN PROBABILITY SAMPLING TECHNIQUE
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The characteristics of the universe: the universe is the total population characteristics of the research area, its figurative and demographic characteristics. The knowledge of this by a researcher would go a long way in determining the method of data collection and the instrument to be administered together with the proportion of the sample that will serve as a representation of the entire universe.
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Sample frame: A sample frame is a guide or a list containing all the elements within the population of study. As a method, probability sampling, especially with the use of simple random sampling (SRS), demands that the researcher provides a sample frame as a guide or parameter for sampling out study participants.
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Ethics of Research: this is important because, ethics set boundaries or limits to researchers so as to effectively achieve objectivity in the research process. The researcher must bear in mind, these prescribed ethics so as to come up with a valid and reliable data.
THE APPLICABILITY OF PROBABILITY SAMPLING TECHNIQUE IN AFRICAN RESEARCHES
Probability sampling technique is generally used in survey researches which have to do with quantitative method of data collection and analysis. Mainly, academic researches by students and professors within the social science discipline make use of probability method in conducting researches. This is based on the rationale that it is easier and efficient including reliable in data generalization.
Probability sampling technique to some degrees, can be applied to African studies because, there are professionals who have been grounded in such areas of research. However, there are some cultural and environmental constraints within Africa that can limit its validity and reliability. The problems exist in diverse categorizations; ranging from dark figures, the non-receptive study participants to researches, unavailability of appropriate sampling frame etc.
In probability sampling, the assumption is that the sampled elements will be a representative of the characteristics of the entire population under study. However, in African settings, probability sampling is not necessarily sufficient for obtaining results that con be generalized with “confidence” to the entire population. This concerns the response rate of the sampled elements because, once a sample is selected, and attempt made to collect the data through questionnaires from all the sampled elements, in practice, researchers never obtains 100% of the sample due to some unforeseen situations such as, some sampled members may inevitably travelled, hospitalized, incarcerated, away at school, or in the military. Others may be due to work schedule, community involvement, or social life, or others may simply refuse to participate in the study, even after the best efforts of the researcher to persuade them (A brief introduction to sampling, n.d).
The effect of this kind of problem to African research is that non-participation from any sampled element, “biases” the final sample usually in unknown ways. The response rate describes the extent to which the final data set can be used to generalize to the entire study population; therefore, a high response rate is extremely important when results will be generalized to the larger population. The lower the response rate, the greater the sample bias which is typical of African researches using probability sampling technique (Robert 1994).
In respect to the above, we shall look into some of the problems that militate against a good level of applicability of probability sampling in African context.
PROBLEMS ASSOCIATED WITH PROBABILITY SAMPLING APPLICABILITY IN AFRICA
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Sampling frame: A sampling frame is a list or set of directions for identifying the target population (Malhortra 1999:30). In other words, sampling frame consists of all the elements within a target population from which a sample could be drawn. In probability method, sampling frame is necessary using the simple random technique, which requires the availability of the sampling frame, however, this poses a lot of challenges in African studies because, in many occasions, records are scarcely available to present the researcher the required sampling frame, or in many occasions, the available ones may not be accurate reflection of the target population. According to UNESCO (n.d), the main problem of probability method in African context is the fact that probability sampling in the use of simple random sampling requires a complete presentation of the universe or population from which the sample is to be drawn and then, the possibility of obtaining an up to date list of the population is not often guaranteed in African contexts. There are always “dark figures” in African situation which hinders a proper application of the ideals of probability method. For instance, in a research that has to do with domestic violence against women, it requires that the researcher obtains all the sampling frame or the list of all the women that are victims of domestic violence but, because such records may either not be documented by the appropriate agencies, one finds out that the little record the researcher makes use of, may not actually reflect the entirety of all the victims of domestic violence hence, devaluating the essence of probability method in African context.
According to Lanre (1997), there are always “dark figures” which implies unreported or undocumented cases which if not taken into consideration, may hinder an accurate information gathering, leading to false data.
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Non Receptiveness of individuals to Academic Researches: the non receptiveness of individuals to academic researches is another important factor which limits the scope of probability sampling technique in African context. This problem can lead to difficulty in information gathering or faulty information. When individuals feel reluctant to give out information, two issues can occur; (a) the individuals choose to fulfill all righteousness by supplying false information in the questionnaire. i.e., they can tick anything they wish just to discharge the researcher. (b) The individuals can also withhold the questionnaires which often lead to shortage of sampled instruments. All these have great effects on the data generalization.
For instance, if the respondents give false information based on their reluctance to give out information, the researcher would only analyze based on what he or she obtains from the field which will be generalized to the entire population but in empirical terms, that information are not accurate thereby, creating a vacuum within the probability method application. Therefore, generalizing with such data, leads to false generalization.
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Cultural beliefs/values: certain norms, values and beliefs are considered sensitive in many African societies. Issues of reproduction, sexual behaviors, HIV/AIDS status, rape and family problems etc are considered sensitive by most African societies. Hence, the tendencies of probability sampling technique to select respondents that will give accurate information on the above cultural issues are not guaranteed. According to a web article “A brief introduction to sampling, n.d”, a situation where probability sampling is not necessary is when a researcher wishes to describe certain characteristics of a particular group in an exploratory way.
Thus, the type of instrument designed for the sampled elements may in some situations, provoke feelings that would make the respondents withdraw from the study or give wrong information to the researcher (Morris 2005). For instance, a researcher may find it difficult studying about adolescent sexual behavior in Nigeria or incidences of rape using the probability sampling method. This is because; such issues are considered sensitive and should not be disclosed openly. The same goes to a study on HIV/AIDS carriers where individuals fail to disclose their status because of the stigma attached to such conditions. Unlike the western societies where individuals have the willingness to open up to their mental and emotional challenges, which researches help to uncover, the African situation is different hence, presenting difficulties for researchers to adopt the probability technique in choosing the participants for a study. Hence, researchers choose to dodge from embarking on studies that has to do with cultural issues and invariably leading to poor statistics on such areas of interest. For instance, a researcher would find it difficult to study issues that has to do with female reproductive behaviors in the Northern part of Nigeria where the Hajias (wives to Alhajis) to be seen in an open environment. Apparently, a researcher cannot use a probability sampling technique in such instances because, the females there are culturally forbidden from coming out at will not even to have a close contact with another man. Therefore, in such situations, it is very difficult for male researchers to uncover issues concerning women in such cultures using probability sampling technique. These and other cultural issues are prevalent within African context and hinder the quality application of the probability sampling technique.
Thus, the argument in this work is not that probability sampling technique has no application capacity in Africa rather; the emphasis is that, there are many socio-cultural issues that hinder its effective application. According to Bradley (2002), the ability of researchers to understand and take into consideration, the epistemological and methodological issues in African research context, the easier it becomes for them to understand the best way to approach a study dealing with probability method. Hence, one cannot say that probability sampling has no applicability within African context; rather, the possibility of erroneous data generalizations can be inevitable due to the numerous explained environmental and cultural challenges.
CONCLUSION
Probability sampling method is a veritable one which has proved worthy of its reliability especially within the context of the societies that apply the ethics of its usage and will prove the same in African context if the pros and cons associated with its applicability are taking into consideration. Hence, researcher should focus attention on devising methods to overcome the cultural and attitudinal barriers of African societies.
REFERENCES
A Brief Introduction To Sampling (n.d). Retrieved July 2012 from,
Ezeah, P.C. (2004). Foundations of Social Research Methods. Enugu: John Jacob’s classic publishers LTD.
Lindsey, L. and Beach, S. (2002), Sociology. Second edition, New Jersey: Prentice-Hall, Inc.
Malhorta, C. (1999). Sampling. In Muzammil, H.eds. Retrieved July 2012 from
Muzammil, H. (2012). Sampling Method in Social Research. Retrieved July, 2012 from
Robert, J. (1994). Probability Sampling Method. Retrieved July 2012 from, http://www.google.com/gwt/x?hl=en&u=http://e-university.wisdomjobs.com/research-methodology/chapter-1858-355/sampling-fundamentals.html&q=Sampling+may+be+defined+as+the+selection+of+some+part+of+aggregate+or+totality+on+basis+of+which+judgement....&sa=X&ei=7877T96MO4nb0QWLsaHaAQ&ved=0CCEQFjAG
UNESCO (n.d). Nigeria Project for Revitalization of the Instructional Material. Retrieved July 2012 from,