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Biology > Data Analysis > Flashcards

Data Analysis Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Give reasons why standard deviation is more useful than range when comparing variations

A
  • not affected by outliers (anomalies)

- allows statistical tests to be calculated

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2
Q

Suggest why variables are controlled in an investigation

A
  • observe effect of dependent variable alone to allow comparison
  • control variables for validity
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3
Q

Suggest how to approximate highest and lowest value of a distribution given mean and standard deviation

A

mean plus/minus two times standard deviation

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4
Q

Suggest why control in drugs test is given existing treatment

A

unethical to give no treatment for (life threatening) health condition

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5
Q

Suggest what is given to a control group and why

A
  • placebo given which similar to test in every way expect for having effect
  • eliminate variables not due to treatment
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6
Q

Describe how scientists decide how many trials are appropriate

A
  • test different numbers of trials
  • select which ever gives best results in appropriate time / number of trials after which there is no change in sample collected
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7
Q

Gives reasons for carrying out repeats

A
  • exclude anomalous results
  • calculate more reliable mean
  • allow statistics to be carried out
  • check results are concordant
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8
Q

Factors to consider when drawing a conclusion on data

A
  • standard deviation overlap
  • whether statistic is calculated
  • if statistic shows significant trend
  • how highly significant trend is
  • could other factors influence result
  • will experimental model give same effects in reality
  • compare conclusion to experiment
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9
Q

Evaluate mean as a measure of average

A
  • takes into account all data so gives accurate representation
  • distorted by outliers
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10
Q

Evaluate median as a measure of average

A
  • less effected by outliers

- not suitable for small data sets with large variation

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11
Q

Evaluate mode as a measure of average

A
  • unaffected by outliers
  • may not give accurate representation of data set
  • could be multiple or no mean
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12
Q

Tips for describing data

A
  • increase/decrease
  • gradually/ rapidly
  • between ______ and _______
  • highest/lowest at _______
  • fluctuates/CONSIDERABLE variation which may be due to chance
  • start and end same / different
  • _______ higher/lower than _______ throughout
  • follow similar pattern / describe pattern EXACTLY
  • never say CHANGE - specify increase/decrease
  • do not describe graph if asked what effect it shows (interpret!)
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13
Q

Describe how a statistical test would be used to find a significant correlation or difference (in means or frequencies)

A
  • construct a null hypothesis
  • carry out statistical test to calculate test statistic
  • look up value in critical value table for p=0.05
  • use figure to accept or reject null hypothesis (if test statistic is greater than critical value then reject null hypothesis)
    CANNOT SAY USE CALCULATED VALUE TO ACCEPT/REJECT NULL HYPOTHESIS
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14
Q

Give a reason why student t test is the appropriate statistical test for this investigation

A

testing significant difference between TWO MEANS

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15
Q

Give a reason why Spearman’s rank is the appropriate statistical test for this investigation

A

testing significant correlation between two DIFFERENT CONTINUOUS variables

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16
Q

Give a reason why chi-squared is the appropriate statistical test for this investigation

A

testing significant difference between CATEGORICAL data

17
Q

What do results from statistical tests suggest about correlation or differences in data being due to chance

A

p>0.05 means likely due to chance

p<0.05 means unlikely due to chance (p

18
Q

Points to include in conclusion

A
  • difference/ correlation significant or not
  • reject or accept null hypothesis (even if not stated in question)
  • contextual description of what this means
  • (justification using statistical tests)
19
Q

What does significant means

A

not due to chance

20
Q

Suggest why standard deviation might be a better measure of variation in a population than range

A
  • ranges could be similar
  • suggests similar variation in populations
  • standard deviation smaller in one population
  • suggests more uniform distribution in one population compared to another
21
Q

Points to include when evaluating a conclusion

A
  • positive or negative correlation (draw line of best fit)
  • correlation does not necessarily mean causation
  • other factors could affect that have not been tested
  • give evidence from data that opposes conclusion/ state variation in results
  • statistical test not carried out / standard deviation bars overlap so difference could be due to chance
  • be specific to conclusion (affect could be different in humans or only certain subjects tested which may not represent conclusion)
  • repeats not been carried out
  • limitations of control used
  • additional limitations investigation (e.g. factors which may affect results that were not controlled unless told otherwise)
22
Q

Evaluate whether stated value is most effective/highest from data

A
  • not all values tested
  • intervals tested are not small enough
  • most effective/highest value could lie in this interval (state possible interval based on trend in data)
23
Q

Describe how to plan an investigation to test a hypothesis

A
  • state all factors which need to controlled and state how
  • mention a suitable control if relevant
  • mention a large enough sample needs to be taken
  • describe how data will be collected
  • determine if data collected is significant using a statistical test
24
Q

Suggest why a large sample size is taken during an investigation

A
  • representative

- minimise effect of anomalies

25
Q

Suggest why samples are taken randomly during an investigation

A

avoid bias

26
Q

Suggest why a scatter graph is suitable to plot

A

determine correlation between discrete/ independent variables

27
Q

How to carry out an investigation to test for difference between populations

A
  • random sample
  • large enough to be representative
  • measure
  • calculate mean AND standard deviation
  • student t test
  • check for significance
28
Q

Points to remember when doing a biological drawing

A
  • sharp pencil
  • scale bar
  • ruled lines
  • no shading / sketching
  • title / heading
  • label line should not overlap
  • continuous lines
  • state magnification
  • correct proportions
29
Q

When suggesting limitations to a method

A
  • measurement taken standardised (possibility for bias/subjective??)
  • are all necessary factors controlled/ standardised
  • random selection of sample to avoid bias

Biology (14 decks)

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