QC Sec 4 Science & Tech flashcards
QC Sec 4 Science & Tech · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Independent variable
- The factor deliberately changed or selected by the experimenter in a controlled investigation; it is plotted on the horizontal axis and its effect on the dependent variable is measured.
- Dependent variable
- The factor measured as the response in an experiment; its value is expected to depend on the independent variable and it is plotted on the vertical axis.
- Control group
- A comparison group that receives no treatment or an inactive placebo, allowing the effect of the treatment to be separated from other influences on the outcome.
- Confounding variable
- An unmeasured factor that changes along with the independent variable and can therefore produce or mask an apparent effect, making the result ambiguous.
- Random assignment
- Allocating participants or samples to treatment groups by chance so that known and unknown characteristics are distributed evenly, reducing systematic bias between groups.
- Double-blind procedure
- A design in which neither the participants nor the researchers recording outcomes know who received which treatment, preventing expectations from biasing the results.
- Fair test
- An investigation in which only the independent variable is changed while all other relevant conditions are held constant, so any effect can be attributed to that variable.
- Negative control
- A sample or group expected to show no response to the treatment; if it does respond, the method or equipment is producing a spurious signal.
- Correlation versus causation
- Two variables changing together does not prove one causes the other; a confounding factor or reverse direction could explain the observed association.
- Falsifiability
- A property of a scientific hypothesis meaning some conceivable observation or experiment could show it to be false; untestable claims are not empirically scientific.
- Statistical significance
- A result is statistically significant when the probability of obtaining it by chance alone, if no effect existed, is below a chosen threshold such as 0.05.
- Standard error of the mean
- A measure of how precisely a sample mean estimates the population mean, calculated as the sample standard deviation divided by the square root of n.
- Peer review
- Independent experts assess a study's methods and reasoning before publication; it screens for flaws but does not itself replicate the findings.
- Replication
- Repeating a study with new samples or by other researchers; consistent results across independent replications strengthen confidence that a finding is real.
- Sample representativeness
- The degree to which a sample reflects the larger population, determined mainly by how subjects were selected rather than by sample size alone.
- Accuracy versus precision
- Accuracy is how close a measurement is to the true value; precision is how closely repeated measurements agree with each other, independent of the true value.
- Random error
- Unpredictable variation in measurements that scatters results above and below the true value; averaging repeated readings reduces its effect on the mean.
- Systematic error
- A consistent offset that shifts all readings in the same direction, often from miscalibration or faulty technique; it is not reduced by averaging and requires correction.
- Percentage error
- The absolute difference between a measured and an accepted value, divided by the accepted value and multiplied by 100, expressing deviation as a percentage.
- Significant figures
- The digits in a measurement that carry meaning about its precision; the last reported digit should be the first uncertain one.
- Dimensional analysis
- Checking or deriving an equation by comparing the base units of each term; both sides of a valid equation must have identical dimensions.
- Order-of-magnitude estimate
- A rough calculation using rounded values and known reference quantities, used to judge whether a precise answer is plausible.
- Reading uncertainty
- The unavoidable imprecision in reading an instrument, typically half the smallest scale division for analog devices and one unit in the last digit for digital displays.
- Slope as rate of change
- On a linear graph, the slope equals the change in the dependent variable divided by the change in the independent variable, carrying units of y per x.
- Error bars
- Marks on a graph showing the uncertainty or spread of each plotted value; overlapping intervals suggest the difference may not be statistically meaningful.
- Logarithmic axis
- A scale on which equal distances represent equal multiplicative factors, so exponential growth appears as a straight line.
- Outlier
- A data point far from the general trend; it should be investigated for measurement error before deciding whether to exclude it from analysis.
- Negative feedback
- A control mechanism in which the output opposes the change that produced it, stabilizing the system around a set point, as in a thermostat.
- Energy efficiency
- The ratio of useful energy output to total energy input, usually expressed as a percentage; the remainder is lost mainly as heat.
- Mechanical advantage
- The ratio of load force overcome to effort force applied by a machine; for a lever it equals the effort arm divided by the load arm.
- Eutrophication
- Nutrient enrichment of water, usually by nitrogen and phosphorus runoff, causing algal blooms and oxygen depletion that can kill aquatic life.
- Trophic energy transfer
- Only about ten percent of energy at one trophic level passes to the next; most is lost as heat and through respiration, limiting food chain length.