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maths skills Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what does standard deviation measure?

A

variation or spread of data about the mean

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2
Q

what is standard deviation a measure of?

A

precision of data

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3
Q

what does a low standard deviation indicate?

A

data have narrow range
points are grouped closely to the mean
greater precision
greater validity
increased confidence in data

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4
Q

what does a high standard deviation indicate?

A

data have large range
points are not well-grouped
lower precision
lower validity
decreased confidence in data

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5
Q

what do the symbols in the equation for standard deviation represent

A

s= standard deviation
∑=sum of
x=value in data set
x̄=mean of data set
n= number of values in data set

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6
Q

how to comment on standard deviation and precision of a data set?

A

higher/lower standard deviation with figures
values vary more/less about the mean
greater/smaller precision

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7
Q

magnification equation

A

magnification= image size/ actual size

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8
Q

what are unpaired t-tests used for?

A

comparing whether there is a significant difference between 2 means

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9
Q

why is the unpaired t-test unpaired?

A

the data was obtained from 2 different organisms

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10
Q

unpaired t-test steps

A

1)state null hypothesis that there is no significant difference between the means (test will tell us to accept or reject it)
2)use data to calculate value for t
3)work out degrees of freedom
4)use critical values table and look at 5% first
5)conclude: is there a significant difference?

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11
Q

what do the symbols in the unpaired t-test represent?

A

x̄=mean of data set
S=standard deviation
S^2=variance
N=number of values in set

|=modulus, makes value positive

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12
Q

how to calculate degrees of freedom for an unpaired t-test?

A

sample size- number of data sets

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13
Q

when are paired t-tests used?

A

when 2 sets of measurements are taken from the SAME organism

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14
Q

what do the different symbols in the equation for the paired t-test represent?

A

đ=mean difference
n=number of pairs of data
sd=standard deviation of the differences

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15
Q

paired t-test step by step

A

1)state null hypothesis
2)work out difference between pairs
3)work out standard deviation of the differences
4)calculate value for t
5)work out degrees of freedom
6)use critical values table to see if there is a significant difference

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16
Q

how to work out degrees of freedom for a paired t-test?

A

n-1

17
Q

what is spearman’s rank correlation coefficient used for?

A

consider relationships between 2 sets of data
tells us whether 2 data sets are correlated or not, and whether that correlation is significant

18
Q

what do the symbols in the equation for spearman’s RCC represent?

A

∑=sum of
D=difference between the ranks
n=number of pairs of data

19
Q

range of spearman’s RCC?

A

value must be between -1 and 1

20
Q

order of ranking for spearman’s RCC?

A

rank from largest (1) to smallest

21
Q

how do you rank for spearman’s RCC if two or more values are the same?

A

they must take the same rank so do the mean of the ranks which the values cover

22
Q

circumference of circle equation

A

2πr

23
Q

area of circle equation

A

πr^2

24
Q

surface area of a cuboid equation

A

2(bh+bl+hl)

25
Q

volume of cuboid equation

A

hbl

26
Q

percentage change equation

A
27
Q

percentage yield equation

A
28
Q

percentage error (uncertainty) equation

A

(2x absolute uncertainty)/quantity measured x100

29
Q

Rf value equation

A

distance moved by solute/ distance moved by solvent

30
Q

rate equation

A

change in quantity/ time taken

31
Q

what format do you write a ratio in

A

x:1

32
Q

how to increase confidence in data

A

increase no. of repeats at each temp, which enables identification of anomalies. if anomalies are present, take more repeats and dilute effect of the anomalies to make a more accurate mean, increasing reliability
calculate standard deviation ad add error bars to mean points on graph. if range is > 10% from mean, less confidence
perform statistical test (e.g. unpaired t-test) to assess the significance of the difference between the means at different temperatures

33
Q

tips describing graph

A

split into 2/3 sections
use data
process data

biology (27 decks)

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