section 1

• what is a hypothesis?


  a statement which might be true or false but there's not enough evidence yet. It must be testable
• what is stage one of an investigation?


  planning - choose a hypothesis, what data and how to collect it
• what is stage two of an investigation?


  collecting data - choose data source and collection method
• what is stage three of an investigation?


  processing and presenting data - choose diagram and measures
• what is stage four of an investigation? 


  interpreting results - analysis to draw conclusions
• what is stage five of an investigation?


  communicating results and evaluating methods
• what are five constraints of planning an investigation?

  time

  costs

  ethical issues

  confidentiality

  convenience
• what is raw data?

  Unprocessed data
• what is quantitative data?


  anything that can be measured with a number e.g. height
• what is qualitative data?


  non-numerical and used words to describe it e.g. eye colour
• what is discrete data?


  something that can be measured exactly e.g. number of points
• what is continuous data?


  data that can take any value e.g. height
• what is a categorical scale?

  they give names or numbers to classes of qualitative data - this is only

  used for labelling the data
• what is an ordinal scale?

  Numerical scale with order.
• what is bivariate data?

  it's made up of two variables
• what is multivariate data?

  it's made up of more than two variables
• what are pros of simplifying tables?

  easier to pick out useful information

  easier to spot patterns
• what are cons of simplifying tables?

  Loss of detail
• how do you simplify tables?

  total the data
• what is class interval?

  the range of a class
• what are pros of grouping data?

  it's easy to read and process

  identify patterns

  compare different classes
• what are cons of grouping data?

  accuracy is lost (no exact data values)

  calculations are only estimates
• what are upper and lower class boundaries?

  values at the top and bottom of the classes
• what is class width?


  the difference between the lower boundary of one group and the lower boundary of the next group
• when would you have unequal class widths?

  when there's lots of data close together have narrower classes

  when the values are more spread out have wider classes
• what are disadvantages of rounding continuous data?


  Loss of precision

  sometimes a rounded values is put in a different class and distorts the data
• what are pros of primary data?


  data will relate directly to the hypothesis

  you have control and know how reliable the data is
• what are cons of primary data?


  it could cost a lot of time and money

  there could be reliability problems

  it may be difficult or impossible to collect some data
• what are pros of secondary data?


  it's easier to access

  it's quick and cheap

  it could be more data than you could collect on your own
• what are cons of secondary data?


  it may be in the wrong format or rounded

  it's hard finding data to match the hypothesis e.g. it may be out of date

  it may be unreliable
• what is a population?


  the group you want to find out about e.g. all the pupils in a school
• what is a census?


  a collection of data from every member in a poulation
• what are some precautions with a census?


  carefully define the population

  it's easier to carry out on a small population
• what are pros of a census?


  it takes in the whole population so the data is accurate
• what are cons of a census?


  it's difficult to do with a big population

  the population may be undefinable
• what is sampling?


  choosing some members from a population
• what are pros of sampling?


  it's quicker, cheaper and more practical
• what are cons of sampling? 


  it's less accurate and may be biased
• what is a sample frame?


  List of all the elements in a population.
• how do you make sample data more representative?


  sample from the correct population

  select items at random

  use a bigger sample