P.08 Recording Quantitative Results
Key Points for Constructing a Results Table
- Clear, Ruled Structure:
- Use ruled lines to separate rows and columns, ensuring clear organization.
- Draw a border around the table for visual clarity and ease of reading.
- Headings and Units:
- Column/Row Headings: Clearly label each column or row with the quantity being measured.
- Units: Use SI units and place units in the headings, not next to individual values within the table.
- Order and Sequence:
- Independent Variable First: The independent variable (e.g., rennin concentration) should be in the first column, arranged from lowest to highest.
- Dependent Variable Columns: Place the dependent variable values (e.g., time to reach end-point) after the independent variable.
- Consistency in Decimal Places:
- Uniform Decimal Places: Record all values of the dependent variable to the same number of decimal places, reflecting the precision of the measurement.
- Mean Values: Keep the mean to the same decimal places as individual measurements for consistency.
- Handling Anomalous Results:
- Identifying Outliers: Anomalous results (outliers) that deviate significantly from other values should be identified (e.g., bold italics).
- Excluding Anomalies: If re-measurement isn’t possible, exclude anomalies from the mean calculation.
- Example: If one reading in the 1% concentration row is an outlier, calculate the mean using only the consistent values.
- Recording Non-Results:
- Did Not Clot: If a reaction does not occur (e.g., milk does not clot at 0% concentration), record as “did not clot” or use infinity (∞) to indicate an unmeasurable time.
- Calculating Rate: Use the formula = 1/time. For samples that did not react, ( 1/∞ = 0), indicating zero rate.
Example of a Well-Organized Results Table
| Rennin Concentration (%) | Time to Reach End-Point (s) | Time to Reach End-Point (s) | Time to Reach End-Point (s) | Mean Time (s) |
|---|---|---|---|---|
| 1st Reading | 2nd Reading | 3rd Reading | ||
| 0.0 | did not clot | did not clot | did not clot | did not clot |
| 0.2 | 67.2 | 68.9 | 67.8 | 68.0 |
| 0.4 | 48.1 | 46.9 | 47.3 | 47.4 |
| 0.6 | 30.1 | 31.9 | 30.1 | 30.7 |
| 0.8 | 20.3 | 19.2 | 19.9 | 19.8 |
| 1.0 | 13.1 | 18.9 | 12.7 | 12.9 |
- Bold Italics: Used to highlight an anomalous result (e.g., 18.9 at 1% concentration).
- Excluding Anomalies from Mean: Calculate the mean for 1% rennin as ( 13.1 + 12.7) ÷ 2 = 12.9).
Summary Tips for Accurate Data Recording
- Design Clear Tables: Organized, neat tables make data easy to interpret and use for calculations or graphing.
- Consistency in Measurements: Use uniform decimal places to maintain clarity and reliability.
- Handle Anomalies Carefully: Mark and exclude anomalies if they cannot be re-measured.
- Document Non-Results: Clearly note instances where no reaction occurs, and adjust calculations accordingly.