COMPARATIVE STUDIES

 

Introduction:  Comparative studies are intended to show possible differences between two or more groups;  In addition to surveys that are cross-sectional, as seen in previous discussions, data for comparative studies may come from different sources; the two fundamental designs being retrospective and prospective.  Retrospective studies gather past data from selected cases and controls to determine differences, if any, in exposure to a suspected risk factor.  These are commonly referred to as case–control studies; each study being focused on a particular disease.  [RETROSPECTIVE STUDIES]  [CROSS-SECTIONAL STUDIES]  

In a typical case–control study, cases of a specific disease are ascertained as they arise from population-based registers or lists of hospital admissions, and controls are sampled either as disease-free persons from the population at risk or as hospitalized patients having a diagnosis other than the one under study.  [CASE-CONTROL STUDIES]  

The advantages of a retrospective study are that it is economical and provides answers to research questions relatively quickly because the cases are already available.  Major limitations are due to the inaccuracy of the exposure histories and uncertainty about the appropriateness of the control sample; these problems sometimes hinder retrospective studies and make them less preferred than prospective ones.

RELATED;

1.  RESEARCH METHODOLOGY

[REFERENCES]

EXPERIMENTAL STUDY DESIGNS

INTRODUCTION:  There are so many types of experimental design that not all of them can be considered within the scope of today’s discussion.  This section, therefore, is confined to describing those most commonly used in the social sciences, the humanities, public health, marketing, education, epidemiology, social work, and so on.  These designs have been categorised as: the after-only experimental design; the before-and-after experimental design; the control group design; the double-control design; the comparative design; the ‘matched control’ experimental design; the placebo design.

THE AFTER-ONLY EXPERIMENTAL DESIGN:  In an after-only design the researcher knows that a population is being, or has been, exposed to an intervention and wishes to study its impact on the population.  In this design, information on baseline that is to say pre-test or before observation, is usually constructed on the basis of respondents’ recall of the situation before the intervention, or from information available in existing records for example secondary sources.

The change in the dependent variable is therefore measured by the difference between the before which act as the baseline, and ‘after’ data sets.  Technically, this is a very faulty design for measuring the impact of an intervention as there are no proper baseline data to compare the ‘after’ observation with.  Therefore, one of the major problems of this design is that the two sets of data are not strictly comparable.  For example, some of the changes in the dependent variable may be attributable to the difference in the way the two sets of data were compiled. Another problem with this design is that it measures total change, including change attributable to extraneous variables; hence, it cannot identify the net effect of an intervention.  

In practice, the adequacy of this design depends on having reasonably accurate data available about the prevalence of a phenomenon before the intervention is introduced.  This might be the case for situations such as the impact of random breath testing on road accidents, the impact of a health programme on the mortality of a population, the impact of an advertisement on the sale of a product, the impact of a decline in mortality on the fertility of a population, or the impact of a change in immigration policy on the extent of immigration. In these situations it is expected that accurate records are kept about the phenomenon under study and so it may be easier to determine whether any change in trends is primarily because of the introduction of the intervention or change in the policy.

RELATED;

1.  BLIND STUDIES 

2.  THE CROSS-SECTIONAL STUDY DESIGN

3.  RESEARCH METHODOLOGY

REFERENCES

EXPERIMENTAL Vs NON EXPERIMENTAL STUDY DESIGNS

 

INTRODUCTION:  In studying causality, when a researcher or someone else introduces the intervention that is assumed to be the ‘cause’ of change and waits until it has produced – or has been given sufficient time to produce – the change, then in studies like this a researcher starts with the cause and waits to observe its effects. Such types of studies are called experimental studies.

NON-EXPERIMENTAL STUDIES

There are times when, in studying causality, a researcher observes an outcome and wishes to investigate its causation. From the outcomes the researcher starts linking causes with them. Such studies are called non-experimental studies. In a non-experimental study you neither introduce nor control/manipulate the cause variable. You start with the effects and try to link them with the causes.

RELATED;

1.  CROSS-SECTIONAL STUDY DESIGNS  

2.  THE REPLICATED CROSS SECTIONAL DESIGN

3.  RESEARCH METHODOLOGY

BLIND STUDIES

 

INTRODUCTION:  The concept of a double-blind study is very similar to that of a blind study except that it also tries to eliminate researcher bias by not disclosing to the researcher the identities of experimental, comparative and placebo groups. In a double-blind study neither the researcher nor the study participants know which study participants are receiving real, placebo or other forms of interventions. This prevents the possibility of introducing bias by the researcher, promoting maximum reliability of the study findings.

RELATED;

1. EXPERIMENTAL STUDIES

2.  RESEARCH METHODOLOGY

CROSS-SECTIONAL STUDY DESIGNS

INTRODUCTION:  Also known as one-shot or status studies, are the most commonly used design in the social and medical sciences. This design is best suited to studies aimed at finding out the prevalence of a phenomenon, situation, problem, attitude or issue, by taking a cross-section of the population. They are useful in obtaining an overall ‘picture’ as it stands at the time of the study.

PROCEDURES:  In this type of study design, data is collected at a single point in time and it will sometimes require the respondents/participants to recall the past experience about the problem under study.

ADVANTAGES OF CROSS-SECTIONAL STUDY DESIGNS:  There are a number of advantages attached to this type of study design.

1.  It is time saving, in that data can be collected in a single and once.

2.  It saves costs of collecting data.

3.  It is one of the best study designs when no follow up is needed.

DISADVANTAGES OF THIS STUDY DESIGN:  This study design comes with disadvantages as well;

1.  It is easy to encounter bias and confounding factors.

2.  Since data is collected at a single point in time, the study design is not good for studying trends of phenomena.

RELATED;

1.  FEMINIST RESEARCH  

2.  EXPLORATORY RESEARCH 

3.  EXPERIMENTAL STUDY DESIGNS

4.  RESEARCH METHODOLOGY

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