How can you collect reliable data?

1. to collect reliable data from letters to the editor in women's and men's magazines you could use a variety of strategies to make the data reliable
Firstly, you should not just gather all your sources from one magazine, that way your data does not show a variety of different sources, and the data you collect from just one magazine, could be bias towards that magazine, and again would make your research flawed.
Another good technique for collecting data like this could be to collect data not just from one particular time period, take for example Christmas, may not be the same agenda of topic than in the summer time, so if you take all your data from summer and not winter(or vica versa)
you should always vary your data and look at different target audiences, for example you shouldn't always look at an all male audience text, or an all female audience text, it would be a good idea to look at catalog and look at how men's and women's products are advertised differently.
2. to collect reliable data about Brian Cox's tweets you could use a few different strategies
you would need to make sure that it was the real Brian Box you were following, not a fake or mock account.
you should not just collect his tweets on there own, you should look at other celebrities tweets to get some idea of context
don't always interpret the text literally, always think about the context of how it was meant, nothing can be truely understood if it sarcastic or ironic over the internet
3. to collect reliable data from Micheal Gove's comments on education
You should look at the audience to which he was speaking to, it could help you to better understand the implicature between what he said and what he meant. Politics always has an implied meaning.
You should collect data from different politicians of different parties, rather than just conservative, different political parties are bound to have different views on how education should be dealt with.