AQA A-LEVEL BIOLOGY STATISTICAL TESTS Questions With
Accurate Answers
Why do we use statistical tests? - Accurate answers Tells us if results are significant or a due to
chance and if the null hypothesis can be accepted or rejected
What does probability mean? How does this apply to scientific research? - Accurate answers The
likelihood an event will occur. We analyse our results at a certain level of probability (At a p<0.05 level,
we can say with 95% confidence that our results were or were not significant. At p<0.01, our confidence
will increase to 99%)
When would standard deviations be an appropriate statistical test to select? - Accurate answers To
investigate the spread around the mean of an individual data set, of which the data has been measured
What do we mean by standard deviations? What type of measure is this? - Accurate answers The
spread of data around the mean - if the value is large, there is a large spread. It is a measure of
dispersion and produces a value like ±x
Give the formula for calculating standard devaition - Accurate answers √∑(x-mean)²/n
How can standard deviation be calculated? - Accurate answers Find the mean of a data set. For
each point in the data set, subtract the mean and square it. Add up this value for each point in the data
set and divide by number of values. Finally, square this answer
How can standard deviations show the significance of results? - Accurate answers If the standard
deviations of two data sets are overlapping, the difference between the two means is not statistically
significant (any difference is just due to chance) If the standard deviation are not overlapping, the
differences in the two means are statistically significant (the differences are not due to chance, but some
other factor)
The standard deviations can be drawn as error bars on graphs, which make the overlapping easier to
identify
Why is the standard deviation a more useful measure of dispersion than the range? - Accurate answers
Less influence by outliers and anomalies
Accurate Answers
Why do we use statistical tests? - Accurate answers Tells us if results are significant or a due to
chance and if the null hypothesis can be accepted or rejected
What does probability mean? How does this apply to scientific research? - Accurate answers The
likelihood an event will occur. We analyse our results at a certain level of probability (At a p<0.05 level,
we can say with 95% confidence that our results were or were not significant. At p<0.01, our confidence
will increase to 99%)
When would standard deviations be an appropriate statistical test to select? - Accurate answers To
investigate the spread around the mean of an individual data set, of which the data has been measured
What do we mean by standard deviations? What type of measure is this? - Accurate answers The
spread of data around the mean - if the value is large, there is a large spread. It is a measure of
dispersion and produces a value like ±x
Give the formula for calculating standard devaition - Accurate answers √∑(x-mean)²/n
How can standard deviation be calculated? - Accurate answers Find the mean of a data set. For
each point in the data set, subtract the mean and square it. Add up this value for each point in the data
set and divide by number of values. Finally, square this answer
How can standard deviations show the significance of results? - Accurate answers If the standard
deviations of two data sets are overlapping, the difference between the two means is not statistically
significant (any difference is just due to chance) If the standard deviation are not overlapping, the
differences in the two means are statistically significant (the differences are not due to chance, but some
other factor)
The standard deviations can be drawn as error bars on graphs, which make the overlapping easier to
identify
Why is the standard deviation a more useful measure of dispersion than the range? - Accurate answers
Less influence by outliers and anomalies
