Processing Data Flashcards
How do you summarise data?
Find the mean and range.
What should you not include in range and mean?
Anomalous results.
What are descriptive statistics? give examples.
Describe patterns in data.
Mean, range and standard deviation.
Why is the standard deviation better than the range?
It tells you how values are spread out about the mean rather than just the total spread of data.
What does a small standard deviation mean?
It means the repeated results are similar and close to the mean.
More precise/accurate.
Why is calculating %’s good?
Helps you to compare amounts from samples of different sizes.
EXAMPLE.
In a DNA molecule containing 3000 bases, 900 of the bases are cytosine. What percentage are cytosine?
Divide 900 by 3000 = 0.30.
Multiply 0.30 by 100 = 30%
What is the formula for % change?
Percentage change = final value - original value divided by original value times by 100.
Positive value = increase.
Negative value = decrease.
Why is calculating % change good?
Helps to quantify how much something has changed.
EXAMPLE.
A person’s blood glucose concentration was 4.2 mmol dm-3 before a meal and 2 hours after the meal it was 6.5 mmol dm-3.
Calculate the 5 change.
6.5 - 4.2 divided by 4.2 times 100 = 55%
The person’s blood glucose was 55% higher after the meal.
Why can ratios be used?
To compare different types of quantities.
EXAMPLE.
Write the ratio 28 : 36 in the form X : 1.
Divide both sides by 36.
28 divided by 36 = 0.78.
36 divided by 36 = 1
So the ratio is 0.78 : 1
What is the first significant figure?
The first digit which isn’t a zero.
The 2nd, 3rd and 4th significant figures carry on immediately after the first even if they’re zeroes.
EXAMPLE.
Round 0.6874976 to 2 s.f and 3 s.f.
- 69 2s.f
0. 687 3s.f
What happens if the calculation involves numbers to different significant figures.
Always give your answer to the lowest number of significant figures used in the calculation.
This is because fewer digits a measurement has the less accurate it is. So your answer can only be as accurate as the least accurate measurement in calculation.
How can you deal with very large or very small numbers?
Convert it into standard form.
How do you change very big/slow answers to standard form?
Move the decimal point left/right.
The number of times the decimal point moves is represented by a power of 10.
Big number = positive. Small numbers = negative.
EXAMPLE.
Write 16,600 in standard form.
Move decimal point to give smallest number between 1 and 10.
Count the number of places the decimal point has moved.
It has moved 4 places to the left.
As its moved to the left the power is positive.
1.65 x 10(4)
TIME.
How do you get from seconds to minutes.
And then minutes to hours.
Seconds to minutes DIVIDE by 60.
Minutes to seconds MULTIPLY by 60.
Minutes to hours DIVIDE by 60.
Hours to minutes MULTIPLY by 60.
LENGTH.
How do you get from nanometres to micrometres
And then micrometres to millimetres.
Nanometres to micrometres DIVIDE by 1000.
Micrometres to nanometres MULTIPLY by 1000.
Micrometres to millimetres DIVIDE by 1000.
Millimetres to micrometres MULTIPLY by 1000.
VOLUME.
How do you get from Centimetres cubed to decimetres cubed.
And then decimetres cubed to metres cubed.
Centimetres cubed to decimetres cubed DIVIDE by 1000.
Decimetres cubed to centimetres MULTIPLY by 1000.
Decimetres to metres cubed DIVIDE by 1000.
Metres cubed to decimetres MULTIPLY by 1000.
Order from smaller to biggest.
Minutes.
Seconds.
Hours.
Seconds.
Minutes.
Hours.
Order from smaller to biggest.
Millimetres.
Nanometres.
Micrometres.
Nanometres.
Micrometeres.
Millimetres.
Order from smaller to biggest.
Metres cubed.
Decimetres cubed.
Centimetres cubed.
Centimetres cubed.
Decimetres cubed.
Metres cubed.
