Standard Deviation Flashcards

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1
Q

what is correlation?

A

when a change in one variable is reflected by a change in the other variable, you cannot conclude that the change in one caused the other

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2
Q

what is a casual relationship?

A

when a variable causes a change in another variable

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3
Q

what is standard deviation?

A

the spread of data from the mean

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4
Q

why is standard deviation better than the range?

A

the range only takes into account the highest and lowest values in the data set , range is more influenced by a single outlier than SD

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5
Q

what does a large SD in relation to the mean suggest?

A

the data is highly variable, less reliable data

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6
Q

what does a small SD in relation to the mean suggest?

A

there is little variation in the data, the values are all very similar, more reliable data

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7
Q

why are 2 SD’s better than 1?

A

2 SD from the mean incorporate 95% of all the data

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8
Q

what does it mean if SD’s overlap?

A

there is not a significant difference between the two sets of data

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9
Q

what does it mean if the SD’s don’t overlap?

A

there is likely a significant difference between the two sets of data

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10
Q

what are some things you must do during a biological investigation to make the data as reliable as possible?

A
  • must have a control group
  • must have all variables that would affect dependant variable controlled
  • must do many repeats, making the mean more reliable
  • assign groups randomly to avoid bias
  • if investigating someone with a serious illness you must allow them to continue regular treatment for ethical reasoning
  • use SD’s
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