Working Scientifically

Question 1

Accurate

Answer 1

How close a reading is to the real anwer

Question 2

How can we make results more precise

Answer 2

By using more precise incerments ( 9.77 instead of 9.7)
By repeating the experement to give an average

Question 3

Independant variablei

Answer 3

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

Question 4

Dependant variable

Answer 4

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

Question 5

Controlled variable

Answer 5

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.

Question 6

Variables

Answer 6

These are physical, chemical or biological quantities or characteristics.

Question 7

Valid conclusion

Answer 7

A conclusion supported by valid data, obtained from an appropriate experimental design and based on sound reasoning.

Question 8

Calibration

Answer 8

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. For example, placing a thermometer in melting ice to see whether it reads zero, in order to check if it has been calibrated correctly.

Question 9

Data

Answer 9

Information, either qualitative or quantitative, that has been collected.

Question 10

Error

Answer 10

See also uncertainty.

Question 11

Measurement error

Answer 11

The difference between a measured value and the true value.

Question 12

Anomalies

Answer 12

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

Question 13

Random error

Answer 13

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.

Question 14

Systematic error

Answer 14

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.

Question 15

Resolution

Answer 15

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

Question 16

Reproducible

Answer 16

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.

Question 17

Repeatable

Answer 17

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.

Question 18

Range

Answer 18

The maximum and minimum values of the independent or dependent variables; important in ensuring that any pattern is detected. For example a range of distances may be quoted as either: ‘From 10 cm to 50 cm’ or ‘From 50 cm to 10 cm’.

Question 19

Prediction

Answer 19

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

Question 20

Interval

Answer 20

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.

Question 21

Hypothesis

Answer 21

A proposal intended to explain certain facts or observations.

Question 22

Fair test

Answer 22

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

Question 23

Evidence

Answer 23

Data which has been shown to be

Question 24

Sketch graph

Answer 24

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.

Question 25

True value

Answer 25

This is the value that would be obtained in an ideal measurement.

Question 26

Uncertainty

Answer 26

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. For example, a length of 56 cm ±2 cm would mean the true value could be anywhere between 54 cm and 58 cm.

Question 27

Validity

Answer 27

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.