Practise choosing a bar chart for one categorical variable and mapping each category to a bar whose height represents its count or sample proportion.
A horticulturist plans a study on the use of compost tea for plant disease management. She obtains 18 identical beds, each containing a random selection of five minipink rose plants. Some bed or beds will not receive compost tea. For those beds receiving compost tea, she plans to use two different composting times (2 and 5 days), two different compost preparations (aerobic and anaerobic), and two different spraying techniques (with and without adjuvants). Midway into the growing season she will check all plants for rose powdery mildew disease.
Using the proportion of plants in each bed that are infected, identify an appropriate graphical representation.
Use a bar chart; each bar height represents the proportion of infected plants in a bed.