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29 Cards in this Set
- Front
- Back
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Define accuracy
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Accuracy is when the value is close to the true value
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What is a causal link
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A change in one variable as a direct result of a change in another variable
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What is a control experiment
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In a good investigation the independent variable is changed and all confounding variables are kept constant. However it may be possible that something else other than the independent variable might have produced the results and a control experiment is used to eliminate the possibility
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What is correlation
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A relationship between two variables. However it might not be a causal one
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What's a dependent variable
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The variable that is measured for each change in the independent variable
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What's a hypothesis
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A possible explanation of an observation or problem that can be tested experimentally
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What's the independent variable
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The variable that is changed by the investigator
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What's a true value?
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The accurate value found when there are no errors
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Define raw data?
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Unprocessed data collected at the time of the investigation
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Define random errors
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Errors that occur in an unpredictable way. This may be caused by human error or by faulty technique in taking measurements or by faulty equipment
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Define reliability
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The reliability of data within a single investigation can be improved by carrying out repeat measurements. Further, if the results of an experiment can be reproduced by other scientists, they are considered to be reliable
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Define zero errors
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Zero errors are caused by instruments that have an incorrect zero. A zero error may occur when the needle on a colorimeter fails return to zero or when the top-pan balance shows a reading when nothing is placed in the pan
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What is a protocol
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Once an experimental method has been shown to produce VALID and RELIABLE results it becomes a protocol used by other scientists
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What is precision
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Little spread about the mean
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What is a fair test
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When only the independent variable has been allowed to affect the dependent variable. A fair test can usually be achieved by keeping all other variables constant or controlled
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What is a control group
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A group treated in the exact same way as the experimental group except for the independent variable being investigated. This allows scientists to make comparisons and ensures that the data that is collected are VALID because any differences between results for experimental group and control group will be due to the INDEPENDENT VARIABLE
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Define evidence
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Data or observations that are used to support a given hypothesis or belief
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What is calibration
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When using a measuring instrument, calibration involves fixing known points and constructing a scale between these fixed points
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What is a double blind trial
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A trial, usually used in the context of medicine when assessing the effects of a new drug or treatment on humans. Neither patients nor scientists know which treatment a particular individual is receiving until after completion of the trial. This helps avoid bias and increases the validity of the trial
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What is a confounding variable
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A variable that may, in addition to the independent variable affect the outcomes of the investigation
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What is chance?
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The results of an investigation could have a genuine scientific explanation but they could be due to chance. Scientists carry out statistical test to assess the probability of the results of an investigation being due to chance
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What is an error
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Errors cause readings to be different from the true value
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Define validity
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Measurements that have been made that are affected by ONLY a single INDEPENDENT variable. Conclusions are only valid if they are supported by valid and RELIABLE data measured to an appropriate level of accuracy
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What are systematic errors
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Errors cause readings to be spread about some value other than the true value fe using a wrongly calibrated instrument
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What are random errors
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Errors that occur in an unpredictable way
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What is a placebo
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A dummy medical treatment given to a control groups in medical trials. The treatment contains no active ingredient but should appear identical to the treatment given to the experimental group. The use of placebo helps ensure that the data collected from the trial are VALID
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What is probability
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Likelihood of an event occurring that can be expressed mathematically
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What is the importance of a large scale trial
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Reduces effect of chance
Allows you to identify anomalies Results are more likely to be representative |
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What is the importance of conducting a trial in different areas?
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Avoids regional bias
There may be factors that affect people living in different areas |
