Statistics
Statistics#
Statistics - Numbers that summarise raw facts and figures in a meaningful way
Analyse data to draw conclusions
Why?#
- Make objective decisions
- Convey meaning
- Make accurate predictions
Statistics are based on facts, but they can be misleading
Visualising Data#
Pie Chart#
- Divide your data into groups, whose frequency when combined comes to 100% of the total.
- They show proportions
- Useful if you want to compare basic proportions
- Less Useful if all the slices have a similar size
Bar Chart#
- Let you compare relative sizes with the advantage of allowing a greater degree of precision
- Ideal for when categories are roughly the same size
- Horizontal or vertical bar graphs can be used
- horizontal better for long field names
The golden rule for showing charts with percentages is to try and indicate frequencies, wither on the chart or just next to it
Otherwise one percentage taken from a few respondents can be compared with a nother percentage from many respondents
What you sometimes need is to show percentages and frequencies…
Split-category Chart#
For each genre you can split into people satisfied and dissatisfied
- Useful for comparing frequencies but difficult to see proportions and percentages
Segmented Bar Chart#
Similar to split categgory but both satisfied and dissatisfied are shown in a single bar
Categories vs Numbers#
Categorical (Qualitive) data is split into categories that describe qualities or characteristics.
Eg. Genre, breed or type
Numerical (Quantitive) data deals with numbers, measurements and counts. It describes quantities.
Eg. weight, length, time
Histogram#
The data being numeric allows us to displays ranges of scores as a continuous scale on an axis.
Histograms are like bar charts but the area of each bar is proportional to frequency and there are no gaps between bars.