3.3 Identifying appropriate graphs

In each of the following cases:

  • Identify the variables;
  • Identify what type of variables these are; and
  • Hence determine and justify the most appropriate graph for displaying the relationship of interest.

In addition, draw a rough example of what the graph may look like.

  1. Meadowfoam is a plant from which oil can be extracted from its flowers, so maximising flowering is important.

    A study (Seddigh and Joliff 1994) examined many individual meadowfoam plants and explored the relationship between the number of flowers each plant produced, and the number of hours of light each plant received.

  1. Early in the 21st century, moves were made to ban smoking in outdoor areas of restaurants, cafes, pubs and bars. However, some people thought this was unnecessary, as they believed that exposure to second-hand smoke was minimal.

    To study this phenomenon and to inform public policy, a New Zealand observational study (Stafford et al. 2010) examined numerous al fresco (open air) restaurants.

    They collected two pieces of information from each individual restaurant: the number of smokers present at the restaurant at the time of observation (restaurants with no smokers; restaurants with one smoker; restaurants with two or more smokers), and the concentrations of fine particulate matter (PM) measured in the restaurant air at the same time. The researchers wish to compare the PM concentrations across the three groups.

  1. To understand the usage of hospital emergency departments (EDs) in Ireland, a study (Curran et al. 2011) examined many individual admissions.

    For each admission to the ED, they recorded if the waiting time was short (within 3 hours) or long (3 hours or longer), and the time of day of the admission (in three divisions: 9am to 5pm; 5pm to midnight; and midnight to 9am).

  1. Stress in children is not as well understood as stress in adults.

    To examine the issue, a study (Saunders et al. 1999) studied many children, and for each child they determined each child's level of playfulness (measured using a quantitative scale called the Test of Playfulness) and each child's level of 'coping' (measured using a quantitative scale called the Coping Inventory).


Curran C, Henry C, O’Connor KA, Cotter PE. Predictors of early arrival at the emergency department in acute ischaemic stroke. Irish Journal of Medical Science. 2011;180:401–5.
Saunders I, Sayer M, Goodale A. The relationship between playfulness and coping in children: A pilot study. The American Journal of Occupational Therapy. 1999;53(2):221–6.
Seddigh M, Joliff GD. Light intensity effects on meadowfoam growth and flowering. Crop Science. 1994;34:497–503.
Stafford J, Daube M, Franklin P. Second hand smoke in alfresco areas. Health Promotion Journal of Australia. 2010;21(2):99–105.