Internal sources of data are those that are internal to the organisation in question. For instance, if you are doing a research project for an organisation (or research institution) where you are an intern, and you want to reuse some of their past data, you would be using internal data sources.
The benefit of using these sources is that they are easily accessible and there is no associated financial cost of obtaining them.
External sources of data, on the other hand, are those that are external to an organisation or a research institution. This type of data has been collected by “somebody else”, in the literal sense of the term. The benefit of external sources of data is that they provide comprehensive data – however, you may sometimes need more effort (or money) to obtain it.
Let’s now focus on different types of internal and external secondary data sources.
There are several types of internal sources. For instance, if your research focuses on an organisation’s profitability, you might use their sales data. Each organisation keeps a track of its sales records, and thus your data may provide information on sales by geographical area, types of customer, product prices, types of product packaging, time of the year, and the like.
Alternatively, you may use an organisation’s financial data. The purpose of using this data could be to conduct a cost-benefit analysis and understand the economic opportunities or outcomes of hiring more people, buying more vehicles, investing in new products, and so on.
Another type of internal data is transport data. Here, you may focus on outlining the safest and most effective transportation routes or vehicles used by an organisation.
Alternatively, you may rely on marketing data, where your goal would be to assess the benefits and outcomes of different marketing operations and strategies.
Some other ideas would be to use customer data to ascertain the ideal type of customer, or to use safety data to explore the degree to which employees comply with an organisation’s safety regulations.
The list of the types of internal sources of secondary data can be extensive; the most important thing to remember is that this data comes from a particular organisation itself, in which you do your research in an internal manner.
The list of external secondary data sources can be just as extensive. One example is the data obtained through government sources. These can include social surveys, health data, agricultural statistics, energy expenditure statistics, population censuses, import/export data, production statistics, and the like. Government agencies tend to conduct a lot of research, therefore covering almost any kind of topic you can think of.
Another external source of secondary data are national and international institutions, including banks, trade unions, universities, health organisations, etc. As with government, such institutions dedicate a lot of effort to conducting up-to-date research, so you simply need to find an organisation that has collected the data on your own topic of interest.
Alternatively, you may obtain your secondary data from trade, business, and professional associations. These usually have data sets on business-related topics and are likely to be willing to provide you with secondary data if they understand the importance of your research. If your research is built on past academic studies, you may also rely on scientific journals as an external data source.
Once you have specified what kind of secondary data you need, you can contact the authors of the original study.
As a final example of a secondary data source, you can rely on data from commercial research organisations. These usually focus their research on media statistics and consumer information, which may be relevant if, for example, your research is within media studies or you are investigating consumer behaviour.
TABLE 5 summarises the two sources of secondary data and associated examples:
Stick to a deadline. Eventually, you have to stop researching and start writing. Determine how much time you’ll need to write (ask your advisor, if you’re not sure). Then, work backwards to determine when you need to conclude your research and begin writing. Without a deadline, you could continue researching forever, and never get to the writing.
Gather all of your data and your sources in one place. As you begin to write, you’ll want to have easy access to your notes and your research. Even if you’ve taken copious notes on a book, you’ll want to also have the book on hand for quoting, citing, and possibly cross-referencing.
Go over your mind map. Make sure that any holes in your research have been filled in with credible sources.
Turn your mind map into an outline.Outlines are crucial to any writing process-- particularly for something as in depth as a dissertation. Turning your mind map into an outline is the first step toward putting your research into a linear order.
Make sure that your outline answers the question of your dissertation. Your outline should include all of the necessary research to prove your thesis, and exclude extraneous research. Your outline should also allow space for your own analysis of the data, which leads to proving your thesis. 
Present your outline to your advisor. Before you begin writing, your advisor should be able to look at your outline and tell you if you’re ready to begin the writing process. Take their feedback seriously, and complete any final research or reorganization before you begin writing.