Experiment words

Question 1

What does it mean if data is repeatable

Answer 1

Repeatable means if the same person does an experiment again using the same methods and equipment, they’ll get similar results

Question 2

What does it mean if data is reproducible

Answer 2

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

Question 3

What does it mean if data is reliable

Answer 3

If data is repeatable and reproducible, it’s reliable and scientists are more likely to have confidence in it

Question 4

What is a valid result

Answer 4

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.

Question 5

What is a fair test

Answer 5

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

Question 6

What is the independent variable

Answer 6

The independent variable is the variable you change

Question 7

What is the dependent variable

Answer 7

The dependent variable is the variable you measure when you change the independent variable

Question 8

What is the control variable

Answer 8

The control variable is the variable you keep the same

Question 9

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

Answer 9

Independent variable
Current

Dependent variable
Potential difference

Control variable
Temperature of the component
The potential difference of the power supply

Question 10

Why are control experiments carried out

Answer 10

Control experiments are carried out as you cannot always control all the variables

Question 11

What is a control experiment

Answer 11

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.

Question 12

What does it mean if data is accurate

Answer 12

An accurate result is a result that is very close to the true answer.

Question 13

What does the accuracy of your results depend on

Answer 13

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

Question 14

What does it mean for data to be precise

Answer 14

Precise results are results where the data is all really close to the mean (average) of your repeated results - data is not spread out

Question 15

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

Answer 15

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

Question 16

What is a random error

Answer 16

Random errors are unpredictable differences caused by things like human errors in measuring

Question 17

Give an example of a random error and explain how it is a random error

Answer 17

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.

Question 18

How to reduce the effect of random errors

Answer 18

You can reduce the effect of random errors by taking repeat readings and finding the mean. This will make you results more precise

Question 19

What is a systematic error

Answer 19

A systematic error is a measurement that is wrong by the same amount every time

Question 20

Give an example of a systematic error

Answer 20

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

Question 21

What won’t correct a systematic error

Answer 21

Repeating the experiment in the exact same way and calculating a mean won’t correct a systematic error

Question 22

What is a zero error

Answer 22

If a systematic error is caused by using equipment that isn’t zeroed properly, it is called a zero error

Question 23

Give an example of a zero error

Answer 23

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

Question 24

What is an anomalous result

Answer 24

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

Question 25

What is discrete data

Answer 25

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

Question 26

What is continuous data

Answer 26

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

Question 27

What is a categoric variable

Answer 27

A categoric variable is a variable based on names or labels

Eye color
Gender
Breed of dog
Level of education

Question 28

What is a quantitative variable

Answer 28

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