The Statistical Cycle

(1) Pose questions/ problems (2) Collect data >Populations and samples >Data collection tools : questionnaire, survey, recording sheets (3) Organise data >Sort data > Frequency tables and tallies (4) Represent data > Pie charts >Histograms >Bar Graphs >Line Graphs (5) Summarise data >Measures of central tendencies( mean, median, mode) > Measures of spread range

Two types of data: Categorical Numerical (Continuous numerical data and Discrete numerical data)

Sources of data collection population sample survey questionnaire interviews observation

Questionnaire example We are conducting a survey to get information about the heights of learners in this school. Please tick the correct box below. Is your height: Shorter than 140 cm? cm? cm? cm? 170 cm or taller?

Example of observation sheet for collecting data Range of heights (cm) Number of learners Shorter than 140 cm 140 cm cm 150 cm cm 160 cm cm Taller than 170

Categorical data cannot be measured numerically but can be described, like the gender of a person (male or female), or the colours of sweets in a jar. Numerical data is data that can be measured by using numbers, like the height of person or the number of books in your bag. Numerical data can be further classified into discrete data and continuous data. Examples of discrete data would be a number of bicycles (1; 5; 8, not half a bicycle!) or the number of puppies in a litter (again: 3 puppies; 6 puppies but not three quarters of a puppy!) Continuous data is data that can have any value - for example, a person's weight may be anything between 50 or 100 kg, including 67,4 kg or 78,3 kg. The amount of rainfall is also continuous data – it can be any amount and is not limited to specific kinds of values (rain does not only fall in 100 ml quantities, for example). There are different ways of collecting data, if we want to collect data on an entire group, we say we collecting data for a population. A sample is a collection of data on a small scale of the population to represent the population. Collecting data from a sample or a population is called a survey. A questionnaire is a predetermined set of questions given to a group of people to complete. When there is verbal communication between two or more people and information is being collected we say this is an interview. Data collection using observation does not involve personal contact. Counting the number of vehicles crossing an intersection every hour would be a good example of observational data gathering.