Natural sciences: when does a measurement support an explanation?
| English | 中文 | Pinyin |
|---|---|---|
| measurement/ˈmeʒəmənt/ | 测量 | cè liáng |
| control/kənˈtrəʊl/ | 控制条件 | kòng zhì tiáo jiàn |
| calibration/ˌkælɪˈbreɪʃn/ | 校准 | jiào zhǔn |
Two readings suggest a simple cause
- Two identical-looking metal cups stand under a lamp. One thermometer reads 28°C and the other 25°C. A student says the cup material alone caused the difference.
- A measurement 测量 links a reading to a method and conditions. Before explaining a difference, check what changed besides the material.
Make the comparison informative
- The cups may differ in distance from the lamp, surface finish, starting temperature or sensor position. Record these conditions and identify the factor the comparison is meant to test.
- A control 控制条件 keeps a relevant condition comparable. Matching distance and starting conditions helps separate a material explanation from these competing explanations.
Why is the first comparison insufficient to isolate material?
Several differences could contribute to the observed result.
Check the instrument and uncertainty
- Compare the sensors in the same stable setting and use an appropriate reference check. Calibration 校准 connects an instrument’s indications to known reference values under stated conditions.
- If one sensor consistently reads higher, switching sensors between cups can reveal that difference. Repeated readings help describe variation, but they do not automatically correct a biased instrument.
Repeated readings automatically remove an instrument’s consistent bias.
A consistent sensor error can recur in every reading.
What can exchanging sensors help check?
The exchange directly tests the instrument-related alternative.
Distinguish a pattern from a complete model
- A stable difference under a controlled comparison may support a material-related explanation. It does not identify every mechanism or establish what happens for all cups and lamps.
- Explain the alternative your method addresses and the alternatives it leaves open. A scientific model earns support from tests and useful predictions; a neat story alone is insufficient.
Which claim best fits a controlled local comparison?
The conclusion is tied to the actual objects and conditions.
Make the knowledge question explicit
- Ask how measurement methods affect confidence in a scientific explanation. Connect your answer to the control checks, instrument checks and the conclusion’s scope.
- Avoid claiming that repeated measurements remove all uncertainty. Explain which uncertainty each check reduces and what further comparison would materially change the judgement.
Match each check to its role.
Different checks address different sources of uncertainty.
Which improvements address the initial problem?
Improve the comparison and instrument checks instead of repeating a confounded setup.
The 28°C cup is closer to the lamp, and its sensor reads 1°C higher in a shared reference setting. The original comparison cannot isolate material. The student first checks the sensors, matches the cups’ position and initial conditions, then records repeated observations with sensors exchanged. A remaining pattern would support a more careful claim about this comparison. It would still need an account of the method’s uncertainty and the range of conditions tested.
Repeating a confounded comparison produces more records of the same problem. Improve the comparison as well as the number of readings.
Connect a scientific claim to a controlled comparison, instrument checks, uncertainty and a stated range of conditions.