When we learn research methodology research designs plays an important role. The research design is a structure of a scientific work. It refers to the overall strategy that you can choose to integrate the different components of the study in a coherent and logical way. A good research design will obviously describe the strategy to be employed for choosing samples, collecting data, managing costs along with other factors which are important for conducting a research. There are different kinds of experimental research designs
Experimental design refers to structure of an experiments or the framework of an experiment. It tries to investigate cause and effect association by demonstrating what outcomes occur when particular factors are experimented and sometimes vary greatly in goal and scale, but always rely on repeatable procedure and logically analysis the results. Experimental design provides methods of hypothesis testing. Hypothesis is the heart of the experimental research. After the researcher defines a problem he has to propose a terminative answer to the problem or a hypothesis. Then he tests the hypothesis and confirms or disconfirms it.
There are three types of experimental design;
1. Controlled experiments
2. Natural experiments
3. Field experiments
A controlled experiment is scientific test that is manipulated by an individual or a group, in order to test single variables at a time .The variables being tested is the independent variables, and is adjusted to see the effects on the system being studied. In control experiments there are two groups. One group receives a change in a certain variable, while the other group receives a standard environment and conditions .This group is called as the controlled group while the other group is known as the experimental group. For further clarification let’s see an example;
There are two identical pots with same size and both contain ten bean seeds planted in the same type of soil , and the both pots are placed near the same window to get necessary sunlight . In fact, there is only one thing that differ here is the way of watering to the pots.
• One pot of seeds get watered every afternoon.
• The other pot of seeds doesn’t get any water at all.
After a week, the seeds in the watered pot have sprouted while none of the seeds in the dry pot have sprouted. Moreover it is clear that the “seeds need water to grow” hypothesis is probably correct.
Natural experiment is an observational study in which a situation or an event that allows for the random or seemingly random assignment of study subjects to different groups is exploited to answer a particular question. Natural experiments are often used to study
Field experiments apply the scientific method to experimentally examine an intervention in the real world rather than in the laboratory.
The features of experimental design are;
• It shows the better directions for better results.
• The given results are easy to interpret.
• It provides conclusions that have reasonable and external validity.
• It includes the plan for analysis and reporting of the results.
The data collecting procedure of experimental design are;
• Identify the variables of the study.
• Develop a detailed plan for collecting data.
• Collecting the data.
• Describe the data, using relevant techniques ( tests, observations, questionnaires )
• Interpret the data and make decision.
• Identify possible errors.
When doing an experimental research there are some steps to follow as follow;
• Identify the research problem. Here the researcher must have a better understanding about the specific problems.
• Then conduct a literature search. Once the researcher identifies the problem, a literature search is conducted. it is a helpful for the researcher to create a good design.
• Determine the research method.
• Conduct the research and test hypothesis
• Analyze the data
• Formulate conclusion.
There are strengths and weaknesses of experimental design too,
• Tighter control of variables
• Easy to comment on cause and effect
• Relatively easy to replicate
• Very practical
• Set the stage for further research
• Artificial environment- low realism
• Demand characteristics – participants aware of experiments, may change behavior.
• Low validity
Longitudinal design is an observational research method in which data is gathered for the same subjects repeatedly over a period of time. Longitudinal research projects can extend over years or even decades. In a longitudinal study, the same individuals are observed over the study period. Furthermore longitudinal analysis can be identified as a micro level analysis.
The data collection procedures of longitudinal analysis are;
• observing individuals or groups
• Taking field notes
• Using or taking photography
• Structured or semi structured interviews.
The steps of research are;
• Statement of the problem
• Identification of information.
• Development of data collecting.
• Identification of target sample.
• Designing of collected information.
• Analysis of data.
There are some strengths and weaknesses in longitudinal design too
• It brings the benefits of extended time frames.
• It shows how changing properties of individuals fit in to systematic change.
• It is useful for establishing casual relationships and for making reliable inferences.
• It separates real trends from chance occurrence
• Economical in that a picture of the sample is built up over a time.
• Sampling errors reduced as study remains with the same sample over time.
• It takes a lot time for the studies to be conducted and the results to emerge.( time consuming )
• Problem of securing participation as it involves repeated contact.
• Data, being rich at an individual level, are typically complex to analyze
• Problems of sample mortality heighten over time and diminish initial representativeness.
In the longitudinal study the choice of data collection, sample size, cost, accessibility is done and decides by the researcher. Firstly he thinks about the research objectives and the budget. And then identifies the major collection methods of data used in longitudinal study, it can utilize either primary data or secondary data. Data collection approach is considered by some researchers to constitute a 3rd category, namely, field experiments
Descriptive design is a study designed to depict the participants in an accurate way. The three main ways to collect this information in descriptive design are; observational, defined as a method of viewing and recording the participants. Case study defined as an in-depth study of an individual or group of individuals. Descriptive research includes much government backed research such as the gathering of a broad range of social indicators and economic information. The main purpose of descriptive research design is the description of the state of affairs as it exists at present. Main characteristic in this descriptive design is that the researcher has no control over the variables; he can only report what has happened or what is happening.
There are some features found in descriptive design.
• Descriptive research ascertains prevailing conditions of facts in a group or case under study.
• The variables or the conditions studied in descriptive research are not usually controlled.
• It gives either a qualitative or quantitative, or both, description of the general characteristics of the group or case under study.
• Study of conditions at different periods of time may be made and the change or progress place between the periods may be noted or evaluated for any value.
The data collection procedure of descriptive design is;
• Case study individuals
• Survey specific topic
The steps of descriptive research design are;
• Identify issues and opportunities for collecting data
• Select issues and set goals
• Plan an approach and methods
• Collecting data
• Analyze and interpret data
• Act on results
There are some strengths and weaknesses can be found in descriptive design they are ;
• Cheap and simple to conduct.
• Utilize routinely collected health statistics.
• Exposure data often only available at area level.
• Differences in exposure between areas may be bigger than at the individual level.
• Utilize geographical information systems to examine spatial framework of disease and exposure.
• Generate hypotheses to examine at the individual level.
• Measures of exposure are only a proxy based on the average in the population.
• Potential for systematic differences between areas in recording disease frequency. Potential for systematic differences between areas in the measurement of exposures.
• Lack of available data on confounding factors.
A meta-analysis design is an analytical methodology designed to systematically evaluate and summarize the results from a number of individual studies. The purpose is not to simply summarize existing knowledge, but to develop a new understanding of a research problem using synoptic reasoning. The main objectives of meta-analysis include analyzing differences in the results among studies and increasing the precision by which effects are estimated.
To fulfill the validity of Meta analysis research, it should clearly defined objectives, including precise definitions of the variables and outcomes that are been evaluated and a well-reasoned and well documented justification for identification and selection of those studies.
In addition there are some weaknesses and strengths of Met analysis too. These are the features of Meta analysis design.
In Meta analysis design the data collection procedure is followed as below.
Meta-analysis should be viewed as an observational study of the evidence. The steps involved are similar to any other research undertaking: formulation of the problem to be addressed, collection and analysis of the data, and reporting of the results. Researchers should write in advance a detailed research protocol that clearly states the objectives, the hypotheses to be tested, the subgroups of interest, and the proposed methods and criteria for identifying and selecting relevant studies and extracting and analyzing information.
A meta-analysis is usually preceded by a systematic review, as this allows identification and critical appraisal of all the relevant evidence .the general steps Met analysis is as follows;
• Formulation of the research question.
• Search the literature
• Selection of studies
• Decide which dependent variables or summery measures are allowed.
• Selection of Met analysis model.
• Examine sources of between-study heterogeneity, for example using sub group analysis
• Meta-analysis can only be as valid as the studies selected for the systematic review.
• When high quality studies are available and the methodology of the meta-analysis is sound, the conclusions of the review are likely to be reliable.
• when the methodological quality of the available studies is insufficient, then
Conclusions drawn from quantitative combining of these data might also be inadequate.
• the choice of the study outcome can be influenced by the results (outcome reporting bias);authors tend to report primarily the outcome with the most favorable result and suppress other outcomes with no significant results.
• Can provide valuable contributions to science because they enable the assimilation of the information in the particular field.
• The volume of the literature makes it simply to read.
• Provide reliable information
• Summarizes many of the data.
• Many of the specific steps provide such systematic reviews with their procedural superiority over narrative reviews.
Research design is needed because it facilitates the smooth sailing of the various research operations, thereby making research as efficient as possible yielding maximal information with minimal expenditure of effort, time and money. Just as for better, economical and attractive construction of a house, we need a blueprint (or what is commonly called the map of the house) well thought out and prepared by an expert architect, similarly we need a research design or a plan in advance of data collection and analysis for our research project. Research design stands for advance planning of the methods to be adopted for collecting the relevant data and the techniques to be used in their analysis, keeping in view the objective of the research and the availability of staff, time and money. Preparation of the research design should be done with great care as any error in it may upset the entire project. Research design, in fact, has a great bearing on the reliability of the results arrived at and as such constitutes the firm foundation of the entire plan of the research work. In conclusion it is clear and reasonable to conduct a research design in order to resolve certain problems prevailed in the society or relevant area and bring necessary hypothesis or conclusions.
“social research methods” book