Scientific Methodologies
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What is the independent variable in an investigation?
The thing that you change.
What is the dependent variable in an investigation?
The thing that you measure.
What are the controlled variables in an investigation?
The things you keep the same.
Why do controlled variables need to be kept consistent?
So they don’t affect the dependent variable.
Define accurate.
How close the data is to the true value.
Define reliable.
How much the data varies around the mean.
How can reliability be improved?
By collecting more data and calculating a mean.
If an investigation is valid, what does this mean?
There is only one independent variable, all other variables are controlled.
If data is representative, what does this mean?
The data collected reflects the characteristics of the whole population.
If data is anomalous, what does this mean?
A result that differs from the expected result.
What is sampling?
Don’t collect all data but collect a representative sample.
An investigation is collecting the colour of beetles in 12 locations. In each location, 50 beetles colour is recorded. What is the sample size?
50 As the colour of 50 beetles in each location is recorded.
An investigation is collecting the colour of beetles in 12 locations. In each location, 50 beetles colour is recorded. What is the sample number?
12 As 12 different locations are sampled.
When collecting data, why does the data collection technique need to be standardised?
To ensure the data is collected in the same way each time, to eliminate uncontrolled variables.
When would you use random sampling?
To sample an area where there is no change in abiotic factors.
Describe how you would do random sampling.
Produce a grid of the area. Use a random number generator to produce coordinates Collect data at the coordinates.
When would you use systematic sampling?
To sample an area whether there is a change in abiotic factors.
An area when abiotic factors change is also called…
an environmental gradient.
Describe how you would do systematic sampling.
Put down a transect across the environmental gradient. Place a quadrat every 1m. Collect data including measuring the abiotic factor.
What is the difference between a line transect and a belt transect.
A line transect only uses a tape measure- and measure the organisms touching the tape. A belt transect using a tape measure and a quadrat- and measure the organisms in the quadrat at each distance.
What is the difference between a continuous transect and a interrupted transect.
Continuous- record data on everything that touches the tape measure. Interrupted- record data every 1m that touches the tape measure.