• Scientific communication of the results of an experiment are extremely important
• The ideas must be communicated in an appropriate way using appropriate terminology
  • This involves using terms such as?accuracy,?validity?and stating the sources of?random?and?systematic?errors
• Scientists have to design an experiment to answer a question or investigate something
• These will involve?dependent?and?independent?variables
  • An independent variable is what is?changed
  • A dependent variable is what is?measured
  • The?control variables?are what do?not change

• For example, in an investigation of the variation of potential difference and current across a light bulb
  • The?independent variable?is the?potential difference
  • The?dependent variable?is the?current
  • The control variable would be the?temperature?of the apparatus

• Data must always be presented in a scientific way
• This may include:
  • Tables
  • Graphs
  • Diagrams

   

Presenting Data in Tables

• When taking readings, a sensible range should be taken, and the values should all be stated to an appropriate number of significant figures or decimal places
  • This is usually the same number as the?resolution?of the measuring instrument

   

• The columns in any table should have both a?quantity?and a?unit?in their heading
  • When labelling columns, the names of the quantities should be separated from their unit by a forward slash ( / )

   

• For data displayed in a table:
  • The first column should contain the?independent variable
  • The second column should contain the?dependent variable
  • If repeat readings of the dependent variable are required, these should be included with a column for the mean value at the end
  • Any columns required for processing data e.g. calculations should come after this

  

  Conventions for presenting data in a table. The length is the independent variable and the frequency is the dependent variable

   

• In summary, when presenting tables the following must be included:
  • Clear headings, or symbols, for columns
  • Relevant units for measurements
  • Readings listed to the same number of significant figures

   

An example of a correctly labelled table with corresponding graph

Presenting Data on a Graph

• All readings, including suspected?anomalous results, should be plotted on a graph so that they can be easily identified
• When taking repeat readings, it is the?mean?value that is plotted
• The way data is presented on a graph depends on what type of data it is

Discrete data

• Only certain values can be taken, normally a whole number e.g. number of students
  • This should be displayed on a?scatter graph?or?bar chart

   

Continuous data

• Can take any value on a scale e.g. voltage in a circuit
  • This should be displayed on a?line?or?scatter graph

   

Categorical data

• Values that can be sorted into categories e.g. types of material
  • This should be displayed on a?pie?or?bar chart

   

Ordered data

• Data that can be put in ordered categories e.g. low, medium, high
  • This should be displayed on a?bar chart

   

• In summary, when presenting graphs the following must be included:
  • An explanatory title
  • Clearly labeled axes
  • Relevant units for measurements
  • Well plotted points
  • A smooth line or curve of best fit

   

An example of a correctly labelled and plotted graph

Presenting Diagrams

• When presenting diagrams, such as apparatus set-up, all the relevant parts must be clearly labelled

An appropriately labeled diagram of the set-up of an investigation into simple harmonic motion