Error analysis, uncertainties, graphs, evaluating and concluding Flashcards
How can the trend of a graph be represented?
A line of best fit
State the 3 types of correlation and what they mean
- Positive correlation: As one variable increases, the other increases
- Negative correlation: As one variable increases, the other decreases
- No correlation: There is no relationship between the variables
When is a line of best fit curved?
When there is a non-linear relationship between variables
What is a prediction?
A specific testable statement about what will happen in the experiment
What is a hypothesis?
A suggested explanation for a fact or observation
What is a variable?
A quantity which has a potential to change
What is an independent variable?
A quantity that can be changed in an experiment
What is a dependent variable?
A quantity that is measured in an experiment
What is a control variable?
A quantity which is kept the same in an experiment
What is discrete data?
Data that can only take certain values
What is continuous data?
Data that can have any value on a scale
What is categoric data?
Data that can be sorted into categories
What is ordered data?
Categoric data where the categories can be put into order
State the 2 types of errors
- Random error
- Systematic error
What is random error?
An error produced by uncontrollable variables
What is systematic error?
An error produced by experiment apparatus or method
Define calibration
Checking a scale by measuring a known value
What are zero errors?
Measuring instruments falsely reads a non-zero value when the true value being measured is zero
Define uncertainty
An interval in which the true value of a measurement is likely to lie
Define absolute uncertainty
The uncertainty of a measurement given as a certain fixed quantity
Other than absolute uncertainty, how can uncertainty be represented?
- Fractional uncertainty
- Percentage uncertainty
State the equation for fractional uncertainty
Fractional uncertainty = uncertainty/measurement
State the equation for percentage uncertainty
Percentage uncertainty = Fractional uncertainty x 100
What happens to the uncertainty when adding or subtracting data?
The absolute uncertainties are added together
What happens to the uncertainty when multiplying or dividing data?
The percentage uncertainties are added together
What happens to the uncertainty when the data is raised to a power?
The percentage uncertainty is multiplied by that power
How can uncertainty be reduced?
- By doing repeats of the method and finding an average
- By using appropriate equipment, i.e computers or data loggers to measure smaller intervals
How is uncertainty represented in a graph?
By error bars
What are worst lines?
Lines of best fit which have the maximum gradient, going through all error bars
How is the uncertainty of a gradient calculated?
By calculating the worst gradient and best gradient using the error bars and finding the difference between them
How are precise results represented?
By having a smaller amount of spread of data from the mean
What is precision dependent on?
The amount of random error in readings
How are repeatable results represented?
If an experiment can be repeated and the same results achieved
How are reproducible results represented?
If someone else can recreate your experiment with the same equipment or methods and achieve the same results
How can results be valid?
By keeping all the variables apart from the one being tested constant
How can results be accurate?
If the result achieved is really close to the true answer
For a conclusion to be valid, what must it include?
Evidence, valid data arising from the experiment
Define resolution
The smallest change in a quantity that causes a visible change in the reading recorded by the measuring instrument
How can a value be represented as measured to a higher resolution?
By having a higher number of significant figures
What is a reading?
A single value
What is a measurement?
A combination of readings
What is the absolute uncertainty for a reading?
Half the smallest division
What is the absolute uncertainty for a measurement?
Atleast ± the smallest division
State the 6 SI base quantities and their units
- Mass(kilograms/kg)
- Length(metre/m)
- Time(second/s)
- Current(Ampere/A)
- Temperature(Kelvin/K)
- Amount Of Substance(Mole/mol)
