selection of appropriate method for data collection

Complete and appropriate answer of a research question largely depends on the selection of appropriate methods of data collection, which generally begin at the time of selection of a research design. A research question or hypothesis may be answered by using one or more number of methods of data collection. However, selection of appropriate method of data collection is  influenced by several factors as discussed below:
The Nature of phenomenon under study: The nature of the phenomenon under study largely influences the choice of the method of the data collection. Each research phenomenon has its particular characteristics and, therefore, needs different approaches and methods of data collection. For example, some of the phenomenon  only can be studied appropriately through observation such as clinical practices or processes in particular nursing procedures. Similarly, knowledge of a group of nurses only can be assessed through questioning or interviews. Therefore, the nature of the phenomenon under study significantly affects the selection of particular method of data collection.

• Type of research subjects: Data collection methods are also influenced by the type of subjects under study. For example, data  collection from physically or psychologically disabled subjects can be done either by interview or through observation, where data collection through questionnaire is not feasible. On the other hand, if data has to be collected from objects or institutions, questionnaires or interviews may not be possible at all, and researchers will have to depend mostly on observation to collect relevant data.
• The type of research study: Quantitative and qualitative research studies need different methods of data collection. For examples, in qualitative research, more in-depth information is required, therefore, focused group interviews or unstructured participatory interviews are feasible for data collection, while for quantitative research studies more structured interviews, questioning, or observation is used for data collection.
• The purpose of the research study: The purpose of the study also influences the choice of the methods of data collection, such as in a study conducted with the purpose of the exploration of phenomenon, in-depth interviews may be needed for data collection, while studies conducted with purpose of description or correlation of study variables may need more structured methods of data collection.
• Size of the study sample: When a study is conducted on a small sample, interviews or direct observation may be possible, while these methods can be tedious for large samples. For larger samples, questionnaires can be better and more referable methods for data collection. Interviews and observation methods will also be cost-effective and easy for smaller groups, while questionnaires will be convenient, easier and cost-effective methods of data collection for larger samples.
• Distribution of the target population: If target population is spread in a large geographical area, it will not be possible to carry out interviews or observation, and therefore, mailed questionnaires may be a better option, which will be more convenient and cost-effective in such conditions.
• Time frame of the study: If a research is conducted for the long time, it may permit the researcher to use the less-structured methods of data collection to gain in-depth information, while short time-frame studies may not allow the researcher to use the unstructured methods of data collection, where he or she gets very little time for data collection and analysis. Therefore, structured methods of data collection are used more short-term research designs.
• Literacy level of the subjects: Illiterate subjects put constrains on the use of self-responding methods of data collection such as questionnaires. for illiterate subjects, interviews conducted in native language is one of the few possible methods of data collection used, while more varied and numerous options in methods of data collection are available for literate subjects.
• Availability of resources and manpower: Some of the method of data collection require more quantities of resources and manpower, such as conducting interviews and observation compared to the use of questionnaires. Therefore, availability of resources and manpower also affects the selection of methods of data collection.
• Researcher's knowledge level and competence: The researcher's knowledge and competence also affects the selection of methods of data collection, for example conducting an interview observation may require special social and psychological knowledge, skills, and competence, while the use of questionnaires may not demand these skills, however for the development and construction of a good questionnaire, good writing skills may be required.