Experiment words Flashcards
What does it mean if data is repeatable
Repeatable means if the same person does an experiment again using the same methods and equipment, they’ll get similar results
What does it mean if data is reproducible
Reproducible means that if someone else does the experiment, or a different method or piece of equipment is used, the results will still be similar
What does it mean if data is reliable
If data is repeatable and reproducible, it’s reliable and scientists are more likely to have confidence in it
What is a valid result
Valid results are both repeatable and reproducible AND they answer the original question.
Valid results come from experiments that were designed to be a fair test.
What is a fair test
To make an experiment a fair test, everything else that could affect the results should stay the same - otherwise you can’t tell if the think you are changing is causing the results or not
What is the independent variable
The independent variable is the variable you change
What is the dependent variable
The dependent variable is the variable you measure when you change the independent variable
What is the control variable
The control variable is the variable you keep the same
Scenario:
Find out how the current through a circuit component affects the potential difference across the component by measuring the potential difference at different currents
State the
independent variable
dependent variable
control variable
Independent variable
Current
Dependent variable
Potential difference
Control variable
Temperature of the component
The potential difference of the power supply
Why are control experiments carried out
Control experiments are carried out as you cannot always control all the variables
What is a control experiment
A control experiment is an experiment that is kept under the same conditions as the rest of the investigation, but doesn’t have anything one to it.
This is so you can see what happens when you don’t change anything at all.
What does it mean if data is accurate
An accurate result is a result that is very close to the true answer.
What does the accuracy of your results depend on
The accuracy of the results depends on the method - make sure you are measuring the right thing and that you do not miss anything that should be included in the measurements
E.g. estimating the volume of an irregularly shaped solid by measuring the sides isn’t very accurate because this will not take into account any gap in the object
It is more accurate to measure the volume using the eureka can
What does it mean for data to be precise
Precise results are results where the data is all really close to the mean (average) of your repeated results - data is not spread out
Which data set is more precise
REPEAT DATA SET 1 D.S.2
1 12 11
2 14 17
3 13 14
Mean 13 14
Data set 1 is more precise than data set 2 - the range for data a set 1 is smaller than the range for data set 2
What is a random error
Random errors are unpredictable differences caused by things like human errors in measuring
Give an example of a random error and explain how it is a random error
Example of random error:
The errors that are made when you make a reading from a ruler are random
- This is because you have to estimate or round the distance when it is between two marks - sometimes your figure will be a bit above or below the real one.
How to reduce the effect of random errors
You can reduce the effect of random errors by taking repeat readings and finding the mean. This will make you results more precise
What is a systematic error
A systematic error is a measurement that is wrong by the same amount every time
Give an example of a systematic error
An example of a systematic error is if you measured from the very end of your ruler instead of from the 0cm mark every time. All you measurements would be a bit small. Repeating the experiment in the exact same way and calculating a mean won’t correct a systematic error
What won’t correct a systematic error
Repeating the experiment in the exact same way and calculating a mean won’t correct a systematic error
What is a zero error
If a systematic error is caused by using equipment that isn’t zeroed properly, it is called a zero error
Give an example of a zero error
An example of a zero error is if a mass balance always reads 1 gram before you put anything on it, all of your measurements will be 1 gram too heavy
What is an anomalous result
An anomalous result is a result that doesn’t fit in with the rest at all.
You should investigate it and try to work out what happened. If you can work out what happened (e.g. you measured something wrong) you can ignore it when processing your results
Don’t include anomalous results when calculating a mean
What is discrete data
Discrete data can only take exact values (usually collected by counting)
number of plants, number of protons in the nucleus of an atom, the number of marks for a physics paper
What is continuous data
Continuous data can take any value in a given range (usually collected by measuring) e.g. measuring height, weight, mass, depth, length, distance
Continuous data can not be measured exactly
What is a categoric variable
A categoric variable is a variable based on names or labels
Eye color
Gender
Breed of dog
Level of education
What is a quantitative variable
A quantitative variable is a variable based on numeric values
E.g. number of students in a class
Number of square feet in a house
Age
Height
