Today we are taking a look at Frequency and Two-way tables. Frequency tables are created from raw data that have categorised, tallied and then totalled. We can use frequency tables to calculate relative frequencies which can be useful to describe proportions. If the sample is large enough, it can enable us to interpret them as probabilities. Two-way tables provide information about the frequency of two variables and the key to solving problems of this type is to pay attention to the totals column. This will enable you to complete a two-way table accurately and then use the information to calculate probabilities based on the data within the table.
Types of data and Sampling is the foci in today's countdown. You need to be able to recall the types of data and be able to categorise data when it is given to you. Note that there are several categories of data and your information may fit into two or more of these categories. The idea behind sampling is to get a selection of people that will accurately represent the whole population when statistical analysis is carried out. There are two types to be aware of, random (members given a number and then randomly chosen) and stratified (proportionate amount of each group is selected). When dealing with data collection it is always important to think about Bias and whether the data will be collected in a 'fair' manner.