Working Scientifically Terms

Question 1

Accuracy

Answer 1

How close a measurement is to the true value.

Do everything you can to minimise errors

Question 2

Precision

Answer 2

The closeness of agreement between repeats.

(A measurement is ‘precise’ if the values are clustered closely together (around the mean value).

Also, fine measurements (mm) are more precise than large measurements (cm))

Question 3

Fair Test

Answer 3

Where the only thing affecting your dependany variable is your independant variable.

(Control all other variables)

Question 4

Repeatability

Answer 4

A measurement is ‘repeatable’ when the SAME person repeats the experiment (using the same method and equipment) and it gives the SAME (or similar results)

(Compare your own repeat readings or compare with another group)

Question 5

Reproducability

Answer 5

A measure is ‘reproducible if ANOTHER person (or the same person using DIFFERENT equipment/method) can get the SAME or similar results.

(Compare your results to a group with a different method or different equipment)

Question 6

Validity

Answer 6

How useful your evidence is to actually answer the question.

Make sure your experiment tests the right thing and is a fair test

Question 7

Resolution

Answer 7

The smallest preceptible change if a measuring instrument reading e.g ± 1°C for a typical mercury thermometer but ± 0.1°C for a typical digital thermometer.

Question 8

Independant Variable

Answer 8

The variable you CHANGE to see what happens

Put it in the first column if your table, plot in your x-axis

Question 9

Dependant Variable

Answer 9

The variable you MEASURE.

Plot it on your y-axis

Question 10

Control Variable

Answer 10

A variable that must be kept the SAME (or at least monitored) to prevent it affecting your results.

(Controlling variables will help make a FAIR TEST)

Question 11

Continuous Variable

Answer 11

Data that can have a value (“quantity”) anyhwere on a continuum between two extremes. These values can either be COUNTED (e.g number of shrimp) or MEASURED (e.g temperature).

Question 12

Categoric Variable

Answer 12

These variables have values that are LABELS, e.g names of plants or types of material.

(Draw a bar chart)

Question 13

Uncertainty

Answer 13

The inverval within which the true value can be expected to lie.

(Random error and sytematic error contribute to uncertainty. Typically the uncertainty might be estimated as ± half the smallest scale division)

Question 14

Measurement Error

Answer 14

The difference between a measured value and the true value.

‘Error’ does not mean ‘mistake’

Question 15

Random Error

Answer 15

Measurement error due to unpredictable variation from one reading to the next.

(Do your best to control variables. Take repeats and calculate a mean)

Question 16

Systematic Error

Answer 16

Measurement error that is constant or follow a pattern. Environment? Equipment?

(Check your method. Make sure apparatus is calibrated. Check the zero reading of equipment at the start and during the investigation)

Question 17

Zero Error

Answer 17

Any indication that a measuring system gives a false reading when the true value should be zero, e.g an ammeter not returning to zero when no current flows.

(A zero error may result in a systematic uncertainty)

Question 18

Anomaly

Answer 18

A result which clearly doesn’t fit the trend is ‘anomalous’.

Discard anomalous data when calculating your mean