Sources, bias and science in society

Is this source reliable?

A source is where information comes from: a website, a newspaper, a video, a textbook, a scientific paper. Not all sources are equally trustworthy. Before you believe a science claim, check the source.

Here are six good questions to ask. The diagram shows the main ideas in four boxes:

• Who wrote it? Is the author an expert in this area?

• Who paid for it? Does the author or company gain money if you believe it?

• What is the evidence? Are there data, or only opinions and stories?

• How was the evidence collected? How many people or samples? Was it a fair test?

• Can it be checked? Does it name the original study so that others can look it up?

• Do other sources agree? Have other scientists found the same result?

Bias and weak evidence

Bias means presenting information in an unfair way that favours one side. It can be deliberate or accidental.

Common types of bias and weakness:

• Money: a company reports only the results that help to sell its product.

• Small sample: a study of 12 students may not show what is true for all teenagers. Larger samples are more reliable.

• Self-selected sample: if people choose to reply to a survey, they are often the ones with strong opinions.

• No control group: without a group that does not get the treatment, you cannot tell what caused the change.

• Emotional or exaggerated language: words like "deadly" or "miracle" are not scientific.

• Correlation is not cause: two things happening together does not prove one causes the other.

Careful language and checking the original

Scientists choose words carefully. Compare two reports of the same air pollution study in Dublin:

Report B is more precise because it gives numbers, a time period and a comparison. Report A makes a big claim ("deadly") that the data do not show: being 12% above a limit on 5 days does not mean the air is deadly all year.

A conclusion must be supported by the data. Ask: does the evidence really show this?

How can you check the original study?

• Look for the name of the study, the scientists and the organisation (for example a university or Met Éireann).

• Search for the original report rather than relying on a news summary.

• Check the numbers: how many days, how many places, how was it measured?

• See whether other scientists have reached similar results.

Science changes and serves society

Scientific ideas are not fixed forever. When scientists find new evidence, they test it, and if it holds up they change or improve the idea. This is a strength of science, not a weakness. It shows scientists follow the evidence rather than defending old opinions.

Scientists also publish their methods and results. Other scientists then review them (this is called peer review), repeat the experiments and look for mistakes. This makes science more reliable and lets knowledge build up over time.

Science also affects everyday life:

• Vaccines have greatly reduced diseases such as measles and polio.

• Water treatment makes tap water safe to drink.

• Recycling research helps reduce waste going to landfill.

Many developments have benefits and concerns. For example, plastics are cheap, light and hygienic, but plastic waste harms rivers and the sea. Society must weigh the benefits against ethical and environmental concerns, and science provides the evidence to help decide.

Famous scientists show how science helps society. For example, Ernest Walton, from Dungarvan, Co. Waterford, and John Cockcroft were the first to split the atom, using a particle accelerator they built (1932). Jocelyn Bell Burnell, born in Belfast, discovered pulsars. Marie Curie studied radioactivity and her work led to cancer treatments.

Back to the start: you now know why a cold-cure claim from the company that sells the tea should not be believed. You would ask who paid, what the evidence is, how large the sample was and whether others have checked it.

Summary