A researcher stands outside a railway station from 7.30 am to 8.00 am and asks 50 people how they usually travel to work. Of these, 42 say that they usually travel by train.
State the sampling technique used.
Explain why using 4250\dfrac{42}{50}5042 to estimate the proportion of all employed people in the town who travel by train is likely to be biased.
Suggest an improved sampling method.