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# A starting point

Here is a non-exhaustive list of advantages and disadvantages of the three ways to present the data shown above:

The first method, a simple **list**, is easy to create and contains all the raw data i.e. we have the full list of scores. It is not easy to analyse at a glance, however. For example, to identify the highest score or how many students got a score in the 60s, say, you would need to check through each of the 24 scores.

The second method is known as an ordered **stem and leaf diagram**. The scores are presented in order, so it is easier to analyse the data. We can see straight away that the highest score was 81 and we can quickly count the “6 | row” to see that ten students achieved a score in the 60s. A downside is that someone that hasn’t seen stem and leaf diagrams before might be confused. Also, it is not as easy to construct in the first place as a simple list.

The third method, a **bar chart**, is perhaps quite familiar to lots of people. It is easy to see at a glance how many students scored e.g. in the 60s. A downside is that a lot of information is lost; we can no longer tell exactly what scores each student obtained. For example, we cannot tell the highest score from the bar chart; we just know it is something in the 80–89 range. Also, a bar chart is takes more effort to construct than a list or a stem and leaf diagram.

# Part 1 – Reading and constructing stem and leaf diagrams (including back-to-back stem and leaf diagrams)

Back-to-back stem and leaf diagrams are unlikely to be examined at GCSE.**Teachers**: log in to access these.