A Critical Evaluation of Qualitative & Quantitative Research Designs

A wealth of literature demonstrates that research is a discursive practice that must be carried out using meticulous and systematic means so as to meet pertinent norms and standards, especially in regard to its validity, reliability, and rationale (Lankshear, n.d.).

Equally, good quality research must have the capacity to elucidate strong evidence in the form of quantitative or qualitative data that is relevant to a phenomenon or variable under study.

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The development of an effective procedure or guideline of undertaking the research is of paramount importance in the context of allowing objective data to be collected, organized, analyzed and presented in ways that will allow people to acknowledge that the findings are not only informative, but the inferences drawn upon them are logical.

This paper purposes to evaluate some of differences and characteristics between quantitative and qualitative research designs.

Both qualitative and quantitative research studies have unique characteristics. To start with, it is imperative to note that qualitative researchers are mainly concerned with studying the subject matter in the natural settings in an effort to make sense of, or to understand, observable occurrences in terms of the meanings attached to them by people (Patton, 2002).

One of the characteristics of a qualitative research study, therefore, is that it is interested in studying real-world situations or occurrences as they unfold naturally without controlling or manipulating any variables. In essence, it is not predetermined as is the case with quantitative studies.

The second characteristic is that most qualitative studies utilize purposive sampling procedures. Specifically, cases designated for study are selected by virtue of the fact that they have the needed information and provide valuable manifestations of the phenomenon under study.

In most qualitative studies, sampling of cases is aimed at getting more insight about the phenomenon under study, not empirical generalization from a sample of subjects to a population as is the case in quantitative studies (Patton, 2002).

The third characteristic of a qualitative research study is that the design adopted must be open and flexible enough to enable the researcher adapt to new inquiry depending on the level of understanding needed.

A qualitative design must have the capacity to accommodate new situations as they emerge in addition to allowing the researcher pursue new paths of discovery as opposed to a quantitative design, which utilizes rigid, unresponsive design (Patton, 2002).

Quantitative studies, on the other part, are basically undertaken by means of developing a testable hypothesis or research questions, and collecting data, which is then ordered and statistically analyzed to come up with findings. Finally, the inferences from the findings will differentiate whether the original hypothesis is supported by the evidence collected from the field (Creswell, 2003). One of the unique characteristics of a quantitative study is that the researcher is independent from the phenomena under study as opposed to qualitative study, where the researcher must always interact with the phenomena under study.

The second characteristic is that reality in a quantitative study is viewed in an objective and singular manner, intricately separate from the researcher (Creswell, 2003).

A qualitative study, however, views reality in a subjective manner. Finally, the facts collected from the field must be value-free and unbiased, but in a qualitative study, the facts are often value-laden and prejudicial.

The type of research design adopted by the researcher to a large extent influences the sampling method to be used for the study (Patton, 2002). A sampling method, according to Creswell (2003), is basically a technique employed in drawing samples from a larger population in such a way that the sample drawn will assist in the determination of some observations or hypothesis concerning the population.

There exist different types of sampling methods, each with its own practical importance in relation to the kind of research design employed for the study.

As such, most quantitative research designs utilize probability sampling procedures, which includes random, systematic, and stratified sampling techniques. It is imperative to note that in probability sampling procedures, every subject within a population has an identified non-zero chance or probability of being selected (StatPac, 2010)

In random sampling method, the nature of the population must first be defined to allow all subjects equal chance of selection. This is the purest form of probability sampling, and greatly assists quantitative researchers to come up with objective and unbiased data from the field (Creswell, 2003).

In stratified sampling technique, a stratum or a subset of the population that is known to share some common aspects is used to select the sample, thereby reducing sampling error. When the relevant subsets are identified by the researcher and their actual representation in the population known, random sampling is then employed to select adequate number of participants from each subset.

This type of sampling is helpful to a quantitative researcher since it allows him or her to study the subgroups in greater detail while in their own naturalistic world and free from value interferences or bias (Marshall, 1996; Creswell, 2003). Still, this type of sampling assists the quantitative researcher to study some unique subsets within a population that may have low or high incidences of a particular phenomenon relative to the other subsets (StatPac, 2010).

Systematic sampling, on its part, works more or less as random sampling, but selects every Nth member of an already predetermined sample. The technique assists a quantitative researcher to remain objective, and it is also simple to use.

Most qualitative research designs employ non-probability sampling procedures, with the most common type being the convenience and purposeful sampling techniques (StatPac, 2010).

It is however imperative to note that some non-probability sampling techniques such as convenience sampling can be used in quantitative research and some probability sampling techniques such as stratified sampling can also be used in qualitative research (Creswell, 2003).

In a convenience sample, subjects are selected by virtue of being at the correct place at the right time. In short, subjects are selected based on convenience. This is helpful to both quantitative and qualitative researchers since it does not only saves time, but also money (StatPac, 2010).

Due to the depth of information required in qualitative studies, most researchers employ purposive sampling technique to get the participant who is well placed to offer comprehensive and detailed information about a case or phenomena under study (Creswell, 2003).

As such, this technique is not interested in calculating numbers about sampling errors and sample representation as is the case in samples used in quantitative research; on the contrary, a purposive sample is interested in gaining an in-depth analysis of something, and therefore may be value-laden and subjective. However, these externalities form the basis of qualitative research.

As such, it can be said that a sampling method such as random sampling will assist in quantitative research since the nature of the research design is more mechanistic and only interested in coming up with results that can then be generalized to the wider population.

However, a sampling method such as purposive sampling will serve qualitative studies well since they are interested in providing illumination and understanding of complicated issues that can only be answered by the ‘why’ and ‘how’ questions (Marshall, 1996).

Such questions can only be answered by someone who is knowledgeable enough about the case under study, thus the use of purposive sampling.

Second, it is known that for a true random or stratified sample to be selected, the unique aspects under investigation of the whole population must be known before hand. This is only possible in quantitative studies, but is rarely possible in many qualitative studies (Marshall, 1996).

Third, random or stratified sampling mostly used in quantitative research is likely to generate a representative sample only if the underlying characteristics of the study are generally distributed within the population.

However, “…there is no evidence that the values, beliefs and attitudes that form the core of qualitative investigation are normally distributed, making the probability approach inappropriate” (Marshall, 1996, p. 523). Lastly, it is clear that individuals are not equally good at perceiving, understanding, and interpreting either their own or other people’s actions and behavior.

This translates to the fact that while some sampling methods such as random sampling are best suited for quantitative research since the studies are only interested in coming up with results that can be generalized to a wider population, it would appear more plausible for a qualitative researcher to employ a sampling technique such as purposive sampling, which will enable him obtain information that is richer in context and insightful.

Reference List

Creswell, J.W. (2003). Research design: Qualitative, quantitative, and mixed method approaches. Thousand Oaks, CA: Sage Publications, Inc

Lankshear, C. (n.d.). Some notes on the nature and importance of research design within educational research. Retrieved September 25 2010

Marshall, M.N. (1996). Sampling for qualitative research. Family Practice, 13(6), 522-525. Retrieved September 26 2010 http://fampra.oxfordjournals.org/content/13/6/522.full.pdf

Patton, M.Q. (2002). Qualitative research and evaluation methods, 3rd Ed. Thousand Oaks, CA: Sage Publications, Inc

StatPac. (2010). Survey sampling methods. Retrieved September 26 2010


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