Maths Statistics 2015

Probability
1. Key Words:
  1. Notation = P=probability
  2. Event = doing something e.g. flipping a coin
  3. Outcome = result of an event
  4. Equally Likely Outcomes = all outcomes have an equal chance of being chosen
2. You can write the answers in either a:
  1. Percentage %
  2. Fraction /
  3. Decimal 00.000
3. Probability Outcome = number of ways the outcome can happen/total number of possible outcomes
Questionnaires
1. Questioning
  1. Poor Questioning
    1. "You support Arsenal don't you?"
      1. This question is biased because the person being question may feel like the question has already been answered for them.
    2. "What do you think about science? A. it is very grate B. it is grate
      1. In this question there is no negative answer therefore it is a biased question.
    3. " Are you a criminal?"
      1. This question is unlikely to find out the truth in a face-to-face interview.
2. The main methods of questioning.
  1. face to face
  2. by phone
  3. by post
  4. via the internet
3. They generally include
  1. yes/no answers
  2. tick boxes/ multiple choice
  3. numbered responses
  4. word responses
  5. require a sentence to be written
Sampling
1. Discrete and continuous data
  1. Continuous
    1. Definition: can take any value and keeps on going.
    2. E.g. a shoe size.
  2. Discrete
    1. E.g. number of people in a car.
    2. Definition: has to be a hole number, it cant be 3,1/3 for example.
2. Random Sampling.
  1. Ways of calculating it.
    1. Calculator
    2. Computer (excel)
  2. Gives a fair chance to all the numbers.
  3. If you are going to sample people or objects you need to number them.
3. Stratified sampling.
  1. Strata = layer
  2. Sample size for each layer = size of hole sample / size of population *size
  3. Example
    1. there are 180 students in year 7
      1. this is the size of the layer.
    2. there are 1000 students in th school
      1. this is the size of the whole population
    3. you want a sample of only 50 people in total.
      1. this is the whole sample
    4. Now you need to do the sample equation for every year.
Averages
1. Mean
  1. Definition: Mean is an average, it is the 'Centaral' number.
  2. You can calculate it by Adding up all the numbers and the dividing that emount by how many values there are.

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