Ideas about ScienceThese come up in all the science exams – especially the ideas in

context exams

Repeats ?

Repeats – why do you do repeats?

• More reliable (not fairer test!)• Can spot outliers• Can redo outliers• Can calculate mean ( average) – without

outliers

Best estimate / mean?

Best estimate/ mean/ range real difference / outlier

• When taking a set of repeats for an experiment.....

• The mean (average) is the best estimate of the true value

• The range is from the lowest to the highest• An outlier is much higher or lower that the rest of

the results in the range• Real difference in set of results is when ranges

don’t overlap (best estimate is not in both ranges)

Example

• Boris got 2 sets of results• Set A: 10 14 22 12 • Set B: 11 12 13 12

• Outlier(s)? Best estimates/means? Ranges?• Real difference? Why take repeats?

Precautionary principle ?

Precautionary principle

• “Better safe than sorry” principle

• E.g. If you think there is a problem don’t do it

• – people think there might be a danger with young children using mobile phone – so some parents don’t let them have one

• But is all about weighing up the risks and benefits – do the benefits outweigh the risks?

Correlation ?

Correlation ?

• A correlation is a link between a factor and an outcome

• E.g. Hotter the weather the higher the ice-cream sales

• Usually “er” “er” phrase or “more” “more” phrase

• Can you think of some examples?

Causal Link (Cause)

Causal Link

• Causal link is were scientists have proved with reliable studies that the factor causes the outcome

• E.g. They have proved smoking more increases risk of cancer – there is a causal link

Peer reviewed journals

Peer reviewed journals

• Scientist spread their ideas to the wider scientific community in conferences/ seminars and peer reviewed journals

• Peer reviewed journals have the data/tests checked by other scientist – so they are more reliable/ gives more confidence to them

ALARA principle

Alara Principle – ways to reduce the risks

• E.g. If handling radioactive material in your job:

• Stay as far away as possible• Don’t touch it for too long – • Wear protective gear – mask/gloves etc• Get tested regularly/ wear badges to test

levels/ follow health and safety rules

Mechanism ?

Mechanisms ?

• They are starting to call reactions mechanisms• E.g. What is the mechanism for how catalytic

convertor work:• So mechanism in catalytic convertors is ....• 2CO + 2NO 2CO2 + N2

Ethics? Data?

Ethics ? Data?

• Ethics – is the rights and wrongs of doing things depending on your beliefs – e.g. Some people don’t think it is ethically right to give people placebos as it gives them false hope

• Data is information/numbers/figures collected from experiments

Reliable data/ evidence?

For the data/evidence to be reliable and convincing it must have....

• Large sample size /long term study• Blind trials/controls• Variety of ages/genders/regions tested• Can’t just be one persons opinion • Data must be repeatable/confirmed• Unbiased/well designed tests/• Government funded and peer reviewed