Statistics And Maths

Question 1

What is standard deviation ?

Answer 1

The spread of values around a mean.

Question 2

At a standard deviation of +/- 2, if the bars overlap what does this mean ?

Answer 2

The results are not significant, they are likely due to change. We accept the null hypothesis.

Question 3

When would you chose a correlation coefficient?

Answer 3

When looking for an association.

Question 4

When would you chose chi squared test ?

Answer 4

When comparing frequencies.

Question 5

When would you use the students t-test ?

Answer 5

When calculating means

Question 6

If the p value is equal to or lower than 0.05 what does this mean ?

Answer 6

The results are significant, they are not due to chance. We reject the null hypothesis.

Question 7

If the p value is above 0.05 what does this mean ?

Answer 7

The results are not significant, they are likely due to chance. We accept the null hypothesis.

Question 8

At a standard deviation of +/- 2 what does no overlap mean ?

Answer 8

The results are significant. They are not due to chance. We reject the null hypothesis.

Question 9

what is the uncertainty of a reading?

Answer 9

plus or minus half of the smallest scale division.
mass,

Question 10

what is the uncertainty of a measurement

Answer 10

plus or minus 1 of the smallest scale division.
ruler

Question 11

how would you workout percentage error

Answer 11

uncertainty / reading x100

Question 12

how would you make serial dilutions

Answer 12

e.g.
* add 10cm3 of initial concentrated solution to a tube
* add 5cm3 of distilled water to the other test tubes
* add 5cm3 of the previous test tube to the next test tube
* equation for dilution factor = DL = Vi / Vf