science vocab

• Accuracy in measurement is the closeness of a measured result to the true value.
• Calibration involves establishing the relationship between indications of a measuring instrument and standard or reference quantity values, which must be applied.
• Data is information, either qualitative or quantitative, that has been collected.
• Error in measurement is the difference between a measured value and the true value.
• Anomalies are values in a set of results which are judged not to be part of the variation caused by random uncertainty.
• Random error causes 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 causes 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 is 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 is data which has been shown to be valid.
• A fair test is one in which only the independent variable has been allowed to affect the dependent variable.
• Hypothesis is a proposal intended to explain certain facts or observations.
• Interval is the quantity between readings, eg a set of 11 readings equally spaced over a distance of 1 metre would give an interval of 10 centimetres.
• Precision in measurements is the extent to which results are consistent, and depends only on the extent of random errors – it gives no indication of how close results are to the true value.
• Prediction is a statement suggesting what will happen in the future, based on observation, experience or a hypothesis.
• Range is the maximum and minimum values of the independent or dependent variables; important in ensuring that any pattern is detected.
• Repeatable measurement is one where the original experimenter repeats the investigation using same method and equipment and obtains the same results.
• Reproducible measurement is one where the investigation is repeated by another person, or by using different equipment or techniques, and the same results are obtained.
• Resolution is the smallest change in the quantity being measured (input) of a measuring instrument that gives a perceptible change in the reading.
• Sketch graph is a line graph, not necessarily on a grid, that shows the general shape of the relationship between two variables.
• True value is the value that would be obtained in an ideal measurement.
• Uncertainty is the interval within which the true value can be expected to lie.
• Validity is the suitability of the investigative procedure to answer the question being asked.
• Variables are physical, chemical or biological quantities or characteristics.
• Categoric variables have values that are labels, eg names of plants or types of material.
• 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)
• 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.