can refer to

1. Secondary Data Analysis: A Method of which the Time Has Come Melissa P. Johnston, PhD ( Qualitative and Quantitative Methods in Libraries (QQML) 3:619 –626, 2014 )

2. Secondary Data Analysis: Ethical Issues and Challenges

Jaya Prasad TRIPATHY ( Iran J Public Health. 2013 Dec; 42(12): 1478–1479. )

Personally, I think that there is no ultimate answer to your question, because it depends on a wide range of factors, including the actual difference between the initial and the secondary analysis.

Let's consider systematic reviews: indeed, if there is a marked deviation from initially intended purposes, any result of the secondary analysis can be at significant risk of bias, mainly because the literature search (already planned and performed for another aim) may be inadequate to retrieve all available data for this post-hoc analysis.

That is the reason why scientists should write and register a protocol prior to initiating their research study, and any modification of the protocol (due to secondary or post-hoc analyses) should be transparently disclosed and properly justified. This is valid both for primary (clinical trials) and for secondary (literature reviews) studies.

As a practical hint, it is advisable to compare the PICOS (Population, Intervention, Comparison, Outcomes, Study design) criteria of the original research question with the same criteria summarizing the new research question. If there is a sufficient degree of overlap and convergence, then a secondary analysis might be feasible and may provide the scientific community with useful information in a very short amount of time (without conducting another research de novo). This can help to save time, resources and, possibly, to prompt further investigations towards a previously unexpected direction (the so called "serendipity").

All the same, most of the times, it is preferable to stick with the study protocol, ensure the best methodological quality and plan another research if the aim changes after data collection.

Best wishes for your work!

A brief guide designed for clinical workers to understand review methods and findings can be found in the following article:

Article Reading and interpreting reviews for health professionals: a...

Actually, there is no solid answer to this question.

The preference for secondary/primary data primarily depends on the objectives of the research and of course, the availability of secondary data. Traditionally, some researchers or supervisors might accept primary data source as more authentic due to the source unavailability of valid secondary data.

We need to appreciate that research based on secondary data is as rigorous and authentic as research based on primary data. Research supervisors should encourage the use of either source of data depending on the objectives of the research. I personally believe that research using secondary data is less prone to manipulation in comparison to primary data research. It needs to be noted that some of the highly acclaimed and widely cited research papers have employed secondary data sources. There can be variations for the preference of the data source based on the field of research.

Hi,

Let’s in the beginning define what’s the difference between primary and secondary data. The primary data is the original data that researchers collect for a specific purpose. Secondary data, on the other hand, is collected for a different purpose other than the one for which it is used. Also, the secondary data quite often refers to data collected by someone other than the primary investigators. To which extent can we use these data in our research? Its dose mater and depends on many factors, for example, knowing the exact source of the data and how these data had been collected, dose the collected data address the research question, understanding the population size and the targeted groups, etc. Thus, if the all potential factors that may affect the secondary date analysis are excluded and the data is cleaned, planned-well and adds new information to the research question, it can be used as long as it does not alter the fact of the results or the conclusions.

For more information: you can read the following article:

Arigbede et al. (2017): Secondary Data Analysis: Ethical Issues and Challenges, PMID: 28413588

Thank you Moushami Bhattacharya , Michele Antonelli , Sherief Ghozy, Khaled Al-Manei for your valuable inputs.

Most times secondary data are used in systematic review and metaanalysis. The protocols for this type of research are embedded with assessment of biases to determine the quality of included studies and pooling and synthesis of results to produce good recommendations. The increased sample size in pooling several results indictes adequate power.

Thank you very much

It depends on the journal. Some journals are more open to accepting papers based on secondary data. However, the more you show the right level of rigor in collecting and analyzing data, either secondary or primary, the more you enhance the chance of your paper getting published.

The search for primary data should be done after checking and analyzing existing secondary data, to avoid duplicating efforts.

Primary and secondary data analyses serve different purposes. While primary data could be useful for a particular purpose with restrictions to the study population, secondary data pools studies together for purposes of 'generalisation', acquisition of a wider knowledge in one big scoop cutting across ecological divides. So despite its authencity issues, secondary data analysis is key to understanding a global perspective of a particular topic. Also, I think a good understanding of secondary studies is a good foundation for primary research. Secondary data analysis is also cheaper and quicker to put together, but not without its many flaws as you mentioned.

Yes it is worth, the main purpose is model validation over the given compactable data and indeed the accuracy in comparison to the existing approaches in the literature.

Individual primary data may not always be a good source of presence or absence of evidence, but rigorous and robust aggregation of and synthesis of results from primary data is.

Yes, many studies get discarded citing methodological flaws. This is because methodological flaws raise doubts about the validity of studies and their conclusions. hence, it is always looked out for in a systematic review. To be honest just as Sherief Ghozy mentioned, there is no solid answer to the question.