This is the process of selecting samples through different sampling techniques. Then, gather the necessary information. The next step is to organise and present information in a way that can easily analysed and interpreted. There are many ways to represent the data.
Scatter diagrams are used to describe and compare two sets of data. One variable is on the x-axis and the other variable is on the y-axis. Variables on the y-axis are known as dependent variables and they depend on the x-axis.
Jenny sells lemonade. She notices that the air temperature is significant to the number of sales she makes. She makes a list of everyday sales and daily temperature.
From the table, and comparing the two variables in a scatter diagram, it will be:
Each dot corresponds to the temperature and its sales. Temperature is the independent variable while the sale depends on the temperature. As the temperature rises the sales goes up.
Plotting on a scatter diagram is like plotting points of coordinates. The ordered pairs are (33, 8), (25, 5), (34, 15), (35, 17), (36, 17), (39,20) and (35,15). Correlations show the relationship between the sets of two data.
Types of Correlation
A positive correlation is when the results are nearly a straight line and with a positive slope. Like the example above, higher temperature indicate greater sales.
With negative correlation, the results are also nearly a straight line, however, it has a negative gradient. If the given results are that as the temperature rises the sales drop, it is a negative correlation.
No correlation or zero correlation is when the results show no connection between two data.
Stem and Leaf Plot
The stem and leaf diagram is formed by splitting the numbers into two parts.
The result of the mathematics test release, which is the following:
21, 59, 29, 42, 43, 63
49, 64, 65, 45, 33, 51
47, 54, 51, 41, 20, 13
57, 54, 60, 39, 48, 13
58, 12, 51, 33, 31, 37
We can visualize it better by a stem and leaf plot. The data do not need to be arranged in increasing order.
In this example, tens and ones split. The stem is the first digit in tens while the leaf is in one digits.
This means 13, 13, 12.
Bar chart or graphs represent data as vertical blocks. The height of the bar graphs shows the frequency and are separated by a gap. Look at this graph:
This bar graph shows the comparison between the daily sales of jewellery shops. It compares yesterday and today sales of each item.
The pie chart shows the differences or comparison of every variable split between. It’s breaking down data into a number of component parts.
The pie chart shows the following:
29.0% Utilities such electricity, water, and telephone
We can easily distinguish which of the expenses are allocated most.