Practical Skills And Maths Flashcards
When is students t test used
When comparing means
How to go about ‘improve experimental method’ questions
- Changing IV
- Measuring DV
- Controlled variables and a control
- Repeats
- Post results, trends and significance in data
Presentation of data:
Raw data, ruled lines and border
IV in first column, DV in columns to the far right
No calculations in table
Unamibiguous headings in each column with units
Same number of decimal places
Provcessed data up to one sig figure more than raw
What is standard deviation?
A measure of how spread out all the repeats are from the mean
How to calculate percentage changes?
Original - new
Divided by original
Multiply by 100
What is the advantage of using SD instead of the range?
SD shows the spread of data around the mean, whereas range only difference between highest and lowest
SD reduced effect of anomalies whilst range includes them and can be affected by them
SD can be used to indicate whether a difference between results is significant. Therefore SD is useful for coming to a conclusion, if there is no overlap between means and standard deviation likley to be signficnat but can’t be confident
If there is an overlap it is not likley to be significant
Why are logarithms used?
To compare values that have a large range comparing small values to large values
Unit conversions
Cm to mm (X10)
Mm to Um (X1000)
Um to nm (X1000)
How to calculate log value?
On calculator, press log and enter value
There are one unit for log so use original data units
