Defs

• Accuracy


  A measured result that is close to the true value
• Calibration


  Marking a scale on a measuring instrument
• Data


  Qualitative or quantitative information that has been collected
• Evidence


  Data which can be used to support hypothesis
• Fair test


  A test in which the only independent variable has been allowed to affect the dependent variable
• Hypothesis


  A proposal intended to explain certain facts or observations
• Interval


  The quantity between readings, e.g. a set of 5 readings equally spaced over a distance
• Prediction


  An intelligent guess based on some knowledge
• Measurement error


  The difference between a measured value and the true value
• Anomalies


  Values in a set of results which differ from the expected and variation caused by random uncertainty
• Random error


  Causes a reading to be spread about the true value due to results varying in an unpredictable way from one measurement to the next
• Systematic error


  Readings which differ from the true value by a consistent amount each time a measurement is made, they are usually due to the way measuring instruments have been read
• Zero error


  When a measuring system gives a false reading when the measured quantity is zero
• How is an Investigation Carried Out?

  Observations are often the starting points of an investigation
• Independent variable


  In an investigation this is the thing that is actively changed
• Dependent variable


  This variable depends on the independent variable. As the independent variable changes so does the dependent variable
• Control variable


  This is the thing that is kept the same and not changed during the investigation
• Categoric variable


  This is a variable described by a label (qualitative data) such as; the colour of solution which could be green or blue
• Continuous variable


  This is measured variable with a numerical value (quantitative data) such as; temperature which is measured by thermometer
• Planning an investigation


  1. Ensure it is a fair test

  2. Control variables must be kept the same

  3. Control groups must be set up

  4. A risk assessment must be made to ensure the investigation is safe to carry out
• Designing an Investigation


  1. Choose the best values of variables by carrying out trial runs

  2. Select a suitable range for the independent variable

  3. Obtain accurate data by repeating measurements, identifying and discarding anomalies and calculating a mean or by using high-quality instruments

  4. Obtain precise data by using measuring instruments with sufficiently small scale divisions
• Presenting data


  1. Use tables with titles, headings and units

  2. Use bar charts for categoric variables and line graphs for continuous variables

  3. Use a sensible scale, label both axes, draw a line of best fit, label each bar