stats

• What is calculating index numbers used for?

  To compare price changes over time
• What do simple index numbers do?

  Compare the price change of an item with its base year price. The index number for each year is that year's price as a percentage of its base year price
• What does the base year price have a number of?

  100 (100%) - this is the original amount
• Index number formula


  (current price/base year price) x 100
• What does it mean if the index number is greater than 100?

  The value has increased
• What does it mean if the index number is less than 100?

  The value has decreased
• Retail Price Index (RPI)


  Shows rate of change (inflation/deflation) of prices of everyday goods, such as mortgage, food and heating. RPI is calculated by comparing prices to the same month of the previous year - this is because there can be seasonal variations
• Consumer Price Index (CPI)

  Official measure of inflation used by the UK Government. It's similar to RPI but doesn't include mortgage payments. Pensions and benefits in the UK are updated each year in line with the CPI.

  CPI is weighted to reflect the importance of different items in the average shopping basket, and the weightings change each year to reflect consumer spending
• Gross Domestic Product (GDP)


  Value of goods and services produced in a country in a given amount of time. If the GDP falls in two (or more) successive quarters the economy is in recession
• Weighted Index Numbers


  Takes into account proportions (similar to weighted mean). Weightings reflect the importance of different items
• What does the Chain Base Index Numbers do?

  Compare prices from each year with that of the previous year. Show how values change from year to year. The previous year is used as the base year - this means the base year will change every time.

  RPI and CPI are chain base index numbers and show how values change monthly or annually.
• Chain base index numbers equation

  (price/last year's price)x100
• Why do Crude rates have to be recorded?

  They need to be recorded to make plans for the future (high birth rate means more schools will be required)
• What do crude rates tell you?

  How things change in every 1000 - usually births, deaths, marriages or unemployment.
• Crude Rate


  How many times a particular event occurs per 1000 of the population in a given time
• Crude Birth Rate


  Number of births per 1000 of the population
• Crude death rate


  Number of deaths per 1000 of the population
• Crude rate equation


  (number of births or deaths/total population)x1000
• When can crude rates be misleading?

  When used for comparing against another area which has different distribution of ages
• Standard populations


  Represent the whole population. Its a hypothetical population of 1000 people used to represent the whole population, taking into account the number of people with different age/gender/income
• Standard population equation


  (Number in age group/total population) x1000
• Standardised rate


  Allows you to compare the same age group in different populations by using the standard population - allows for more realistic comparisons
• Standardised rate equation


  (Crude rate/1000) x standard population
• How can you find the standardised rate for the entire population?

  Add up the rates for each group
• What is a probability distribution?

  A list of all the possible outcomes together with their expected probabilities
• Binomial distributions


  a type of probability distribution where there are only two possible outcomes
• notation of binomial distribution

  it is written as B(n,p)

  n = number of trials

  p = probability of success
• Conditions for Binomial Distribution


  1. Fixed number of trials (n)

  2. Each trial has 2 outcomes, success (p) or failure (q)

  3. All the trials are independent of each other - the outcome of one doesn't affect the others

  4. Probability of success is constant - it stays the same for every trial
• How to find probabilities using the Binomial distribution (use (p+q)'n)

  1. Identify the 2 outcomes and their probabilities

  2. Expand (p + q)'n

  3. To find the probability of x successes, find the term that has p to the power of x successes ( for 3 successes find the term that has p'3)

  4. Substitute the values of p and q into that term and calculate
• Pascal's triangle


  The coefficients of a binomial distribution follow the pattern of Pascal's triangle.
• The mean (or expected value) of the binomial distribution, B(n,p)

  np (multiply them)
• When are frequency tables used?

  They are a visual method of showing the outcomes of an experiment or trial
• How are two way tables used?

  To display information from a survey or experiment with two variables. An experiment has two variables if the participants can make two choices during the experiment
• What are Bar charts used for?

  Displaying discrete qualitative data
• What is discrete data?


  Data that must take certain numerical values
• What is qualitative data?


  non-numerical, descriptive data
• What are pie charts used for?

  Representing discrete data
• Why are pictograms used?

  They are easy to visualise but aren't always accurate. They use symbols to represent a set frequency of an item, and include a key to show how much of each quantity each symbol represents
• What are vertical line graphs used for?

  Discrete quantitative
• raw data


  unprocessed. Just been collected. needs to be ordered, grouped, rounded, cleaned.