science vocab

• accuracy 


  A measurement result is considered accurate if it is judged to be close to the true value
• calibration 


  Marking a scale on a measuring instrument. This involves establishing the relationship between indications of a measuring instrument and standard or reference quantity values, which must be applied
• data


  information; qualitative or quantitative, that's been collected
• error 


  see also uncertainty
• measurement error 


  the difference between a measured value and the true value
• anomalies 


  values in a set of results which are judged not to be part of the variation caused by random uncertainty
• random error 


  These cause readings to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next. Random errors are present when any measurement is made, and cannot be corrected. The effect of random errors can be reduced by making more measurements and calculating a new mean
• systematic error 


  These cause readings to differ from the true value by a consistent amount each time a measurement is made. Sources of systematic error can include the environment, methods of observation or instruments used. Systematic errors cannot be dealt with by simple repeats. If a systematic error is suspected, the data collection should be repeated using a different technique or a different set of equipment, and the results compared
• zero error 


  Any indication that a measuring system gives a false reading when the true value of a measured quantity is zero, eg the needle on an ammeter failing to return to zero when no current flows. A zero error may result in a systematic uncertainty.
• evidence 


  data which has been shown to be valid
• fair test 


  A fair test is one in which only the independent variable has been allowed to affect the dependent variable
• hypothesis


  a proposal intended to explain certain facts / observations
• interval 


  the quantity between readings
• precision 


  Precise measurements are ones in which there is very little spread about the mean value. Precision depends only on the extent of random errors – it gives no indication of how close results are to the true value.
• prediction 


  A prediction is a statement suggesting what will happen in the future, based on observation, experience or a hypothesis
• range 


  The maximum and minimum values of the independent or dependent variables; important in ensuring that any pattern is detected
• repeatable 


  A measurement is repeatable if the original experimenter repeats the investigation using same method and equipment and obtains the same results. Previously known as reliable.
• reproducible 


  A measurement is reproducible if the investigation is repeated by another person, or by using different equipment or techniques, and the same results are obtained. Previously known as reliable.
• resolution 


  This is the smallest change in the quantity being measured (input) of a measuring instrument that gives a perceptible change in the reading.
• sketch graph 


  A line graph, not necessarily on a grid, that shows the general shape of the relationship between two variables. It will not have any points plotted and although the axes should be labelled they may not be scaled.
• uncertainty 


  The interval within which the true value can be expected to lie. Whenever a measurement is made, there will always be some uncertainty or doubt about the result obtained. Uncertainty can be expressed in terms of spread of values obtained
• validity 


  Suitability of the investigative procedure to answer the question being asked. For example, an investigation to find out if the rate of a chemical reaction depended upon the concentration of one of the reactants would not be a valid procedure if the temperature of the reactants was not controlled.
• variables 


  physical, chemical or biological qualities / characteristics
• categoric


  categoric variables have values that are labels
• continuous 


  Continuous variables can have values (called a quantity) that can be given a magnitude either by counting (as in the case of the number of shrimp) or by measurement (eg light intensity, flow rate etc). Previously known as discrete variable.
• control


  Control variable is one which may, in addition to the independent variable, affect the outcome of the investigation and therefore has to be kept constant or at least monitored.
• dependent 


  Dependent variable is the variable of which the value is measured for each and every change in the independent variable.
• independent 


  Independent variable is the variable for which values are changed or selected by the investigator.