QCAA Agricultural Science EA flashcards
QCAA Agricultural Science EA · 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 researcher between treatments, such as irrigation rate or fertiliser application, so its effect on the measured outcome can be observed.
- Dependent variable
- The variable measured as the response to the independent variable, for example crop yield in t/ha, liveweight gain in kg/day, or soil moisture percentage.
- Controlled variable
- A factor held constant across all treatments, such as soil type, planting depth or temperature, so it cannot confound the observed effect of the independent variable.
- Validity
- The extent to which an experiment measures the variable it claims to measure and the conclusion follows from the data, requiring controlled variables and appropriate measurement technique.
- Reliability
- The consistency of repeated measurements or trials; high reliability means replicates produce similar results, allowing a meaningful mean and measure of variation to be calculated.
- Accuracy
- How close a measured value is to the true or accepted value, improved by calibrating instruments and reducing systematic error rather than by repeating trials alone.
- Replication
- Repeating a treatment multiple times, ideally at least three, so random variation can be estimated and a mean with an associated uncertainty reported.
- Randomisation
- Allocating experimental units to treatments by chance rather than choice, preventing systematic bias from position, soil gradient or operator preference affecting results.
- Control group
- The untreated or standard-practice treatment against which other treatments are compared, providing a baseline to attribute observed differences to the independent variable.
- Systematic error
- A consistent directional error affecting all measurements equally, such as an uncalibrated scale reading high, which shifts results and reduces accuracy but not necessarily precision.
- Random error
- Unpredictable variation in measurements about the true value, reduced by taking more readings or replicates and averaged out in the mean rather than eliminated.
- Percentage error
- Calculated as the absolute difference between measured and accepted values divided by the accepted value, multiplied by 100, expressing measurement deviation relative to truth.
- Mean
- The arithmetic average, calculated by summing all values and dividing by the number of values; sensitive to extreme outliers in small agricultural datasets.
- Median
- The middle value when data are ordered from lowest to highest; resistant to outliers, making it useful for skewed yield, weight or price data.
- Standard deviation
- A measure of spread showing typical distance of values from the mean; a large value indicates highly variable performance within a paddock or herd.
- Coefficient of variation
- Standard deviation divided by the mean, expressed as a percentage; allows comparison of variability between datasets with different units or magnitudes.
- Correlation coefficient
- A value between negative one and positive one describing the strength and direction of a linear relationship between two variables; it does not prove causation.
- Coefficient of determination
- R-squared, the proportion of variation in the dependent variable explained by the regression model, expressed as a decimal or percentage between zero and one.
- Regression slope
- The change in the dependent variable for each one-unit increase in the independent variable, indicating the rate and direction of the relationship.
- Line graph use
- Appropriate when both variables are continuous, especially showing change over time such as monthly pasture growth or seasonal milk production trends.
- Bar chart use
- Appropriate for comparing a measured value across discrete categories, such as mean yield for different fertiliser treatments or breeds.
- Scatter plot use
- Appropriate for displaying the relationship between two continuous variables, such as rainfall versus yield, revealing trend, spread and outliers.
- Water-use efficiency
- The biomass or marketable yield produced per unit of water used, commonly expressed as kilograms per hectare per millimetre of water.
- Feed conversion ratio
- Feed consumed divided by liveweight gain over a period; a lower ratio indicates more efficient conversion of feed into animal production.
- Gross margin
- Gross income from a enterprise minus variable costs, used to compare enterprise profitability without allocating fixed overhead costs.
- Break-even yield
- The yield required so total revenue equals total costs, calculated as total costs divided by price per unit of product.
- Primary source
- Original data or research reported directly by those who collected it, such as a trial report or peer-reviewed experimental paper, generally carrying higher evidentiary weight.
- Secondary source
- A source that interprets, summarises or reviews primary data, such as a review article, extension bulletin or industry magazine, useful but one step removed from the data.
- Source bias
- A systematic slant in a source arising from commercial interest, advocacy or selective reporting, which must be identified and weighed when evaluating claims.
- Synthesis of evidence
- Combining findings from multiple sources to identify where they agree, conflict or leave gaps, producing an integrated answer rather than separate summaries.
- Extrapolation
- Applying findings from one context, such as a specific soil, climate or breed, to a different system where conditions may not hold, requiring explicit caution.
- Confounding variable
- An unmeasured factor that changes alongside the independent variable and can distort the apparent relationship, undermining causal claims drawn from the data.