Presentation on theme: "Organisation and Presentation of Data Hypothesis – This is a statement about the collected data that may or may not be true. The object of using a hypothesis."— Presentation transcript:
Organisation and Presentation of Data Hypothesis – This is a statement about the collected data that may or may not be true. The object of using a hypothesis is to test whether the data fits the statement.
Sample – Because it is not possible to ask everyone a survey question, a sample of people are asked. It is important that the sample of people is representative of the whole group or population to prevent bias!! – The size of sample must be small enough to be representative and large enough to give a valid response to the hypothesis. – You must give reasons for your sample size and choice.
Data can be presented in a variety of ways Line Graph Bar Chart and Histogram Pictogram or Pictograph The following will be in a later presentations 2 Way Tables Pie chart Stem and leaf diagram Scatter-graph
The graph above shows how John's weight varied from the beginning of 1991 to the beginning of 1995. The weight scale runs vertically, while the time scale is on the horizontal axis. Following the gridlines up from the beginning of the years, we see that John's weight was 68 kg in 1991, 70 kg in 1992, 74 kg in 1993, 74 kg in 1994, and 73 kg in 1995. Examining the graph also tells us that John's weight increased during 1991 and 1992, stayed the same during 1993, and fell during 1994. A line graph
Bar chart – All the bars are the same width. – The height or length of the bar indicates the frequency. – Only one axis has a true scale (usually the vertical).
Histograms. The quantity on the vertical axis is frequency density (or frequency per class of a given size). The area of the column representing that class gives the frequency for a particular class of data. The horizontal axis must have a scale. This acts like a normal scale on a graph, with the same distance always representing the same number of units. Note: Histograms are usually used with grouped data.
Pictogram (Pictograph) – Pictures are used and each picture represents a preset amount of data. e.g. a car to represent 1000 cars, or a stick-man to represent every 10 people. – This type of chart is used a lot in tabloid representation of data. It is important that all the pictures are the same size to avoid misrepresenting the data, even if it reduces the artistic quality.
However, all is not well with this particular pictogram.
1.The title is not complete - it should be a full title - for example "Death rates by home fires by age group (England and Wales 2002)" 2.The origin of the data is not stated. The exception to this is if the data is generated from material presented in the report. 3.The axes are not labelled. They should be "Age Group" for the horizontal and "Deaths by 10,000 of population" for the vertical. 4.There is no indication of the sample size e.g. [N=139] to show the size of the survey. 5.There is no figure number e.g. "Fig. 1. Death Rates" so that it can be referred to in the body of the report. Finally, be wary of pictograms, as they may mislead on size. If in doubt use a bar chart.