Collecting Data Keywords

Collecting Data Keywords

1. Types of Data

   • quantitave
     • numerical, dicrete = count, continuous = measure
   • qualitative
     • non-numerical
   • catagorical
     • data can be put into a particular catagory e.g. colour
   • ranked
     • data can be ordered e.g. top 10
   • bivariate
     • two things that can vary e.g. height and weight
   • primary
     • collected by you
   • secondary
     • collected by someone else

2. Data Keywords

   • population
     • All people or objects you're interested in
   • sampling frame
     • list of the population
   • census
     • collecting data from whole population
       • time consuming, expensive
   • opinion polls
     • used before elections to see how country will vote

3. Sampling methods

   • systematic sampling
     • selecting at regular intervals from a list
       • e.g every 2 people
   • simple random sampling
     • number population, select random numbers so everyone has an equal chance
       • You'll need a number table. Number your population. Choose a number from the number table, and read off every 2 digit (or 3 digit) number that is within range of the total number of your population. Keep going till you get your total number.
       • use the '#RAN' button on your calculator, and multiply the number you get by the total amount in your population
   • stratified sampling
     • reflect proportion of population in each group
       • Let's say you have 30 people. 60% are boys, 40% are girls. Rather than use everyone, have a sample of 10. Choose 6 random boys (18÷30=0.6, 0.6 x 10 =6) and 4 random girls (12÷30=0.4, 0.4 x 10 = 4)
   • convenience sampling
     • pick somewhere to stand, ask who come past
       • time consuming, not everyone will respond
   • quota sampling
     • people in sample have to be a particular type
   • cluster sampling
     • population is slipt into smaller groups, the random cluster is chosen