Fundamental Ideas

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Fundamental Ideas
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We all have opinions about lots of things
Are those opinions based on scientific evidence
..
Or are they based on prejudice, whim or hearsay?
Nuclear power is dangerous
Eating fatty foods is bad for you
Computer games are bad
My star sign makes me what I am
Fresh fruit is good for you
We evolved from apes
Friday 13th is unlucky
Smoking is dangerous
We should use less petrol
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Types of variable A variable is something in an
experiment that may have different values
Continuous They can have any value e.g. mass,
temperature, length
Ordered They can have a choice of values e.g.
small, medium or large
Categoric They can only have a definite value
e.g. name of metal, day of week
Discrete They have a numeric value which is a
whole number e.g. number of layers of insulation
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What type of variable are the following?
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In an experiment a change in one variable may
cause a change in another This is a causal
relationship.
The bigger the SPEED of the car The bigger its
STOPPING DISTANCE
The greater the BRIGHTNESS of the light The more
VOLTAGE the solar cells produce
The bigger the NUMBER OF CIGARETTES smoked The
greater the RISK OF CANCER
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The change may be due to association i.e. both
variables change because another variable has
caused them to change
On a hot day trees grow faster On a hot day
people buy more ice-cream On a hot day people
wear less clothing On a hot day people sweat more
Does eating ice-cream make you sweat? Does people
sweating make trees grow faster? Does faster
growing trees make people wear less? Does seeing
people wearing less make you want ice-cream?
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The link may be just due to chance
I won the lottery because I had my lucky red
shirt on