Advantages of systematic sampling ensure even coverage of an area and simplicity. Disadvantages include bias and risk of patterns or under-representation. Systematic sampling is useful for many types of research, including any research types that require looking at individuals, such as human, plant or animal research.
Systematic research basically means picking a percentage of the population to sample, then coming up with a concrete way of choosing that percentage, such as every 10th individual. This is simple method of sampling, making it a good choice for basic research, new researchers or the first steps of more complicated research. When done correctly, this research style provides even area coverage, so theoretically the resulting samples are an accurate representation of the population.
However, with random sampling, it is always possible that the random individuals will not be an accurate representation of the whole population. For example, if every fifth house has four bedrooms, but all the ones in between have two, sampling every fifth house for bedroom number gives a biased result that does not represent the real population. This kind of accidental pattern or bias is a risky disadvantage of systematic sampling, and anyone who samples in this way has to come up with measures to counteract this inaccuracy.