Always consider uncertainty during an experiment, record it in your ELN, and include it in all calculations and reporting . Do not leave the lab until you are sure that you have a valid strategy for determining errors in all final values. Uncertainty Awareness: Before leaving the lab area, ensure you have a valid strategy for estimating uncertainties in all measured and calculated values. Estimating Uncertainty During Measurements: Equipment Uncertainty : Record uncertainties provided by equipment or manufacturers (e.g., balance deviation, pipette error). If unavailable, assume uncertainty is ±0.5 of the smallest measurable unit. Replicates : For three or more measurements, calculate the standard deviation of the mean. Function-Based Values : Perform propagation of error analysis. Least Squares Fitting : Use errors from fitted parameters (e.g., slope or intercept) and propagate uncertainty if used in further calculations. Avoid linear regression if data deviates significantly from linearity. Consult Instructors : Seek help for unclear sources of uncertainty. Propagation of Error: Combine individual uncertainties to estimate the overall uncertainty of the final result. Use partial derivatives where necessary, and assume constants (e.g., RR) are error-free. Reporting Results: Include propagated uncertainty with each result. Compare results with literature values using percent or absolute error. Ensure significant figures reflect uncertainty and justify their use. Replicate Measurements: Report the mean and precision (e.g., standard deviation). Use the Q-test to justify excluding outliers. Single Measurements: Estimate and report uncertainty (random or systematic). Compare accuracy to expected values if available. Least Squares Fitting: Use weighted or non-weighted regression based on data. Reject outliers only using the Q-test on residuals. Propagate uncertainty from fitted parameters to calculated values. Qualitative Uncertainty: For variables with no clear quantitative uncertainty, discuss potential sources and their impact on results. Provide reasonable estimates and substantiate with evidence. Before Leaving the Lab: Confirm all uncertainties are documented. Check for systematic errors (e.g., calibration issues). Ensure thorough records of measured values and associated uncertainties. By following these steps, you ensure your experimental results are accurate, reproducible, and clearly reported.