Practical advantages

• Sociologists save time and money- They are a free source of huge amounts of data. Only the state can afford to conduct large-scale surveys costing millions of pounds e.g Census covering every household in the UK
• Allows comparisons between groups- For example, we can compare statistics on educational achievement, crime rates or life expectancy between classes, gender or ethnic groups
• Collected at regular intervals- they show trends and patterns over time, sociologists can use them fore "before and after" studies to show cause-and-effect relationships