ISA Glossary Terms

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  • ISA Glossary Terms
    • Accuracy
      • A result is considered "accurate" if it is close to the true value.
    • Data
      • Information that has been collected .
      • Qualitative or quantitative.
    • Errors
      • Measurement Error
        • The difference between a measured value and the true value.
      • Anomalies
        • Results which are judged not to be part of the variation caused by random uncertainty.
      • Random Error
        • Cause readings to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next
        • Effects can be reduced by making more measuremens 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.
        • Source of this error could include: environment, methods of observation, or instruments used.
        • Cannot be dealt with by simple repeats. If you suspect a systematic error, the experiment should be repeated using a different technique or equipment, Then compare results.
      • Zero Error
        • Measuring system gives a false reading when the true value of a measured quantity is zero.
          • May result in systematic error.
          • Eg. the needle of an ammeter failing to return to zero when no current flows.
    • Calibration
      • Marking a scale on a measuring instrument.
        • Eg. Placing a thermometer in melting ice to see whether it reads zero.
          • In order to check if it has been calibrated correctly.
    • Evidence
      • Data which has been shown to be valid.
    • Fair Test
      • Only the independent variable is allowed to change the dependent variable
    • Hypothesis
      • A proposal intended to explain certain facts or observations
    • Interval
      • Quantity between readings.
        • Eg. A set of 11 readings equally spaced over a distance of 1 metre would give an interval of 10cms.
    • Precision
      • Very little spread about the mean value.
      • Depends on the extent  only random errors.
        • It gives no indication of how close results are to the true value.
    • Prediction
      • Statement suggesting what will happen in the future.
        • Based on observation, experience or a hypothesis.
    • Range
      • Maximum and minimum values of either variables.
        • Important in ensuring a pattern is detected.
        • Eg. "From 10cm to 50cm" or "From 50cm to 10cm"
    • Repeatable
      • If the original experimenter repeats the exact same investigation and obtains the same results. The measurements are repeatable.
    • Reproducible
      • If the investigation is repeated by another person using different equipment or techniques but obtains the same results the measurements are reproducible.
    • Resolution
      • This is the smallest change in the quantity (input) of a measuring instrument
        • That gives a perceptible change.
    • Sketch Graph
      • A line graph which shows the general shape of the relationship between the variables.
      • No points plotted.
      • Labelled axes. May not be scaled.
    • True Value
      • Value that would be obtained in ideal measurement
    • Uncertainty
      • Interval within which the true value can be expected to lie.
        • With a given level of confidence.
        • Eg. Th temperature is 20degrees Celsius+2 degreees Celsius. At a level of confidence at 95%
    • Validity
      • Suitability of the investigative procedure to answer the question being asked.
        • Eg. An investigation to find out if the rate of a reaction depended on the concentration of 1 of the reactants would not be a valid procedure if the temperature of the reactants was not controlled.
    • Valid Conclusion
      • A conclusion supported with valid data obtained from an appropriate experiment and based on sound reasoning.
    • Variables
      • Categoric Variables
        • Variables that have values that have labels.
          • eg. names of plants or types of material
      • Continuous Variables
        • Variables that can have values that can be given a magnitude either by counting or by measurement
      • Control Variables
        • A variable that has to be kept constant or at least monitored because it can affect the outcome.
      • Dependent Variable
        • The variable where the value is measured for each and every change in the independent variable.
      • Independent Variable
        • The variable in which values are changed or selected by the investigator.

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