4.3 Strengths and weaknesses of the different sources of migration evidence

Migration evidence is migration data that is relevant and provides conclusive proof for a phenomenon or claim (Zinz, 2007). It is sometimes impossible to provide evidence on a migration phenomenon/claim because of insufficient migration data.

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Collecting more numerical migration data may not always give a true picture of how people, organisations or countries are motivated, hence the need for a variety of migration data sources.

Next, you will look at the strengths and weaknesses of the different sources of migration evidence. Table 4.2 covered types of data, but below are some visuals of common examples of evidence, and in what circumstances they can be useful. You may want to use statistical evidence when you have similar data from other countries. For example, you can compare the number of migrants from Nigeria to the United Kingdom with those from Mozambique to the same destination. However, because these two countries have different population sizes, you would need to consider country size first. It is also important to remember that if you also do not have the data separated by sex, age or skill levels, you may not have enough information to explain the figures that you see.


Can you think of a similar example showing how you can use innovative evidence and what possible shortcomings you may find?

The Nigerian Immigration Services collects real time data on the number of passports issued in Nigeria. In fact, the Comptroller General of Immigration Services can see changes in numbers of passports issued and where they are issued from in real time. According to the advantages of this data type you can infer that whoever is watching the data can observe any significant changes in the way the data behaves, for example they can see if a state within the federation shows significant changes in numbers of passports issued on a particular day. However, the type of information collected will have to be limited since there is no consent from the participants to store details such as their gender or ethnicity.

Next read through the flip cards below and answer the questions relating to them in Activity 4.2.

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Activity 4.3 Strengths and weaknesses of migration evidence sources

Timing: Allow 3 minutes
  1. Answer all the questions, using examples from your own experience:
    • a.qualitative data
    • b.administrative data
  2. Think of an instance where administrative and qualitative data were useful.
  3. Can you think of some other pros and cons of administrative evidence in the migration context?
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Here is an example of the kind of answer you might have given:

  1. One problem arising from qualitative data is that you may find the information cannot be generalised to a larger population. This can be a challenge, especially when there are vast differences in the experiences of the respondents. For example:

    ‘Once when we interviewed asylum seekers and refugees, we found some information consistent across the group interviewed, for instance the types of risks encountered on their journey. However, other information was specific to some kind of asylum seekers, for instance one person fleeing political conflict gave examples of how he thought that the host government was collaborating with his origin country embassy to have him returned. This was not verifiable.’

    • a. There are a number of instances were agencies collect administrative data. For example, Migrant Resource Centres collect administrative data on the number of participants in their training programme and this is disaggregated by sex. Attempts to collect this data digitally in order to cover a wider range of respondents sometimes yielded conflicting results. For instance, in some cases respondents said that they had never heard of Migrant Resource Centres but went ahead to affirm that they had registered for a training program there.
    • b. All data types can be useful depending on the purpose for which they are collected. Let us look at administrative data, Frequently, you may want to evaluate the reach or impact of your programme. For example, how many people have you trained in the last month? Or how many of these were male? Administrative data can help you check for a trend, such as if you have increased numbers of persons trained in your programme.
  2. How about qualitative data? In our work on migration qualitative data is very useful to providing in-depth explanations. We may be looking at how return migrants impact upon the country of origin. In Africa, respondents may tell us that return migrants bring ideas about new and productive business cultures from countries they have lived in.
  3. Another benefit of collecting administrative data about routine operations is the cost advantage. Already collected data needs no additional costs especially if we want to use the data to tell us some information about our respondents. For example, the immigration services usually collects information cards at points of entry which provide details about how many foreigners are arriving in the country. In addition to having the information handy when needed, it is difficult to infer this information from surveys after the fact has occurred since foreigners will be dispersed to various parts of the country once they enter.

A disadvantage I can think of is restricted study populations. In the example we gave, the immigration services collected information on arrivals of foreigners at airports. Yet there are many other entry points through which foreigners may come into a country; they may arrive by sea or by land for example. If the information is collected only about those who arrive by air, then we will have a limited population sample that leaves out arrivals through other points of entry.

4.2 Sources of migration data, information and knowledge

4.4 Data and information ownership, responsibility, and control