Measurement Data Flashcards
(20 cards)
What is the independent variable?
The one factor the experimenter manipulates or changes. It is the cause assumed to have an effect on the dependent variable
- Generally found on x-axis or first column of tables
What is the dependent variable?
The factors the experimenter observes to measure the effect of changing the independent variable. - Found on the y-axis of a graph
What are controlled variables?
Other factors an experimenter keeps constant in an experiment to increase confidence that any change seen is caused by the independent variable
What is accuracy?
How close the experiment is to the true value of the quantity being measured
What is the true value?
The value, or range of values, that would be found if the quantity could be measured perfectly
What are systematic errors?
Results in measurements that differ from the true value by a consistent amount each time you measure
What are systematic errors caused by?
- Improper selection and/or use of equipment
- Equipment that has not been calibrated correctly
- Poorly controlled experimental design
How can accuracy be improved?
- Use calibrated instruments
- Select appropriate equipment
- Select sensitive equipment to measure small increments in quantitative change
- Use equipment properly
- Control all variables expect IV
- Reproducibility
What is precision?
Refers to how closely a set of measurement values agree with each other
What are random errors?
Unpredictable variations in the measurement process and result in a spread of readings
How can precision be improved?
- Repeatability
- Increase the sample size or number of replicates
- Use equipment properly
When is a measurement said to be valid?
If it measures what it is supposed to be measuring, so this relates to the equipment being used to conduct measurements
- If measurements are valid, they are also accurate
When is an experiment said to be valid?
If it investigates what it sets out or claims to investigate, so this relates to the design of the experiment
What is repeatability?
Refers to the collection of multiple data sets via concurrent trials (i.e same equipment, same experimenter, same trial)
What is reproducibility
Refers to the collection of multiple data sets via disparate trials (i.e. different equipment or experimenter or times)
What is qualitative data?
Non-numerical and presented as written observations (hence is usually more subjective in its interpretation)
What is quantitative data?
Numerical and can be represented by a variety of graphs (usually more objective in its interpretation)
What are random errors?
Cause unpredictable variations in the measurement process and result in a spread of data
What are systematic errors?
Cause predictable variations in measurements, whereby the displacement of data is consistent and directional
- Sources of systematic error include faulty calibrations of a measurement device or faulty readings by a user (e.g. parallax error)
- Systematic errors affect the accuracy of a measurement
What are personal errors?
Not measurement errors but instead refer to mistakes or miscalculations made by an experimenter
