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What is determinate error? An indeterminate error?

Short Answer

Expert verified
Determinate error is a predictable, consistent error; indeterminate error is an unpredictable, random error.

Step by step solution

01

Understanding Determinate Error

Determinate errors, also known as systematic errors, are consistent and predictable errors that occur in measurements. These errors have a known source and can often be eliminated or corrected with calibration or adjustment. Examples include instrumental errors, environmental errors, and human errors.
02

Understanding Indeterminate Error

Indeterminate errors, also known as random errors, occur without a predictable pattern. These arise from unpredictable fluctuations in experimental conditions or measurements, and they can't be corrected through calibration. Consequently, they can result in variations that are sometimes above and sometimes below the true value, averaging out over multiple measurements.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

random errors
Random errors are natural fluctuations that occur when taking measurements. Unlike systematic errors, these do not have a consistent direction or magnitude and are inherently unpredictable. This means they can cause the measurements to oscillate both above and below the actual true value.
The sources of random errors can include:
  • Environmental changes, such as temperature fluctuations.
  • Limitations in instrument resolution or precision.
  • Inherent variability in the measurement object or process.
Random errors can't be completely eliminated, but they can be reduced by taking multiple measurements and averaging the results. By doing so, the random fluctuations tend to cancel each other out, leading to a more accurate estimate of the true value.
Nonetheless, it's important to assess and report the margin of error in any experimental measurements to account for these variations.
measurement errors
In scientific experiments, measurement errors are inevitable. They're the deviations from true values that occur when measuring quantities. These errors can significantly impact the reliability and accuracy of experimental results. Measurement errors are generally categorized into two types: systematic and random errors.
Systematic errors, or determinate errors, are predictable and consistent. These are often due to faulty equipment, calibration errors, or experimental setup. Once identified, they can sometimes be corrected or minimized.
On the other hand, random errors, or indeterminate errors, result from unpredictable variations. Every measurement contains some level of random error, and recognizing this helps scientists make appropriate corrections. To better ensure measurement accuracy:
  • Calibrate instruments correctly to minimize systematic errors.
  • Use well-maintained equipment capable of higher precision.
  • Take multiple measurements and average them to reduce random errors.
Understanding these error types allows scientists and engineers to design better experiments and interpret their data accurately.
error correction
Error correction involves methods and practices aimed at reducing or compensating for errors in measurements. While it may be impossible to eliminate all errors, significant improvements in accuracy can be achieved with effective strategies.
For systematic errors, correction methods might include:
  • Regularly calibrating instruments to ensure they are giving accurate readings.
  • Using references or standards to cross-check measurements.
  • Ensuring consistent experiment conditions to avoid environmental biases.
Random errors, being less predictable, require a different approach. Averaging several measurements, as mentioned earlier, can help smooth out these errors and provide a more reliable result.
Statistical methods, such as regression analysis, can also be applied to make estimations even more precise.
Having a robust error correction mechanism supports the validity of experimental conclusions and helps build confidence in scientific research outcomes.

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Most popular questions from this chapter

A standard serum sample containing 102 meq/L chloride was analyzed by coulometric titration with silver ion. Duplicate results of 101 and 98 meq/L were obtained. Calculate (a) the mean value, (b) the absolute error of the mean, and (c) the relative error in percent.

This question addresses the following: Use of quality control sample to evaluate method accuracy, use of a significance test to compare two methods, sample homogeneity and data precision. The question is based on actual data collected by students for a senior research project. The lead content of ancient Roman bronze coins can be used to approximate their age. Lead concentrations in individual coins can vary from single percent's up to over \(20 \% .\) A method was developed to quantify lead in bronze coins that utilized hot plate digestion of the samples followed by flame atomic absorption spectrophotometric measurements. Hot plate temperatures can be difficult to set and are often uneven across the apparatus surface, however. As well, a quantitative transfer of the digest solution is required. A second, more efficient method was then developed that utilized a programmable temperature feedback digestion block with volumetric vessels. Data were collected using both digestion methods as provided below. Four coins (numbered \(1-4\) ) were divided in half with a sample from each half (designated as a and b) being digested and analyzed. Also, a standard reference material, NIST SRM \(872,\) was analyzed using both methods; the certified lead content in this material is \(4.13 \pm 0.03 \% .\) Evaluate the data. Comment on accuracy and precision. How could the homogeneity of lead in the bronze coins affect precision? Is one method "better" or "different" than the other? How could this be shown quantitatively? $$ \begin{array}{lrr} \text { Coin } & \text { Hot Plate Method (\%) } & \text { Digestion Block Method (\%) } \\ \text { 1a } & 14.44 & 15.37 \\ \text { 1b } & 8.41 & 7.24 \\ \text { 2a } & 23.77 & 24.14 \\ \text { 2b } & 27.23 & 24.87 \\ \text { 3a } & 6.34 & 6.77 \\ \text { 3b } & 8.04 & 7.34 \\ \text { 4a } & 16.16 & 17.20 \\ \text { 4b } & 19.07 & 18.26 \\ \text { NIST SRM 872 } & 4.21 & 4.12 \end{array} $$ An Excel file for the solution is in the website supplement.

The standard deviation established for the determination of blood chloride by coulometric titration is \(0.5 \mathrm{meq} / \mathrm{L}\). What is the \(95 \%\) confidence limit for a triplicate determination?

You work in an analytical testing lab and have been asked by your supervisor to purchase new pH meters to replace your old supply. You have identified four potential suppliers and now need to evaluate the performance of each pH meter. You obtained a solution with a known \(\mathrm{pH}\) of \(5.5 .\) You performed 10 replicate measurements of the \(\mathrm{pH}\) of that known solution using each of the four different pH meters and obtained the data shown below. $$ \begin{array}{llll} \text { pH } & \text { pH } & \text { pH } & \text { pH } \\ \text { meter } & \text { meter } & \text { meter } & \text { meter } \\ \text { Brand A } & \text { Brand B } & \text { Brand C } & \text { Brand D } \\\ 5.6 & 5.5 & 5.8 & 7.0 \\ 5.8 & 5.6 & 5.9 & 6.9 \\ 5.6 & 5.5 & 6.0 & 6.8 \\ 5.5 & 5.6 & 5.9 & 7.0 \\ 5.6 & 5.6 & 5.3 & 6.9 \\ 5.7 & 5.6 & 5.6 & 6.9 \\ 5.6 & 5.4 & 5.7 & 7.0 \\ 5.7 & 5.5 & 5.8 & 6.8 \\ 5.1 & 5.5 & 5.9 & 6.9 \\ 5.6 & 5.4 & 5.1 & 6.9 \end{array} $$ All other factors being equal (cost, ease of use, etc), which brand would you suggest the lab purchase? Explain your reasoning.

You have developed a new method to measure cholesterol levels in blood that would be cheap, quick and patients could do tests at home (much like glucose tests for diabetics). You need to validate your method, so that you can patent it! Use the information given below and the various statistical methods of data validation you have learned to evaluate the effectiveness of your new testing method. (a) NIST makes a cholesterol in human serum standard that is \(182.1_{5} \mathrm{mg} / \mathrm{dL}\). Your method reports values of 181.83,182.12,182.32 and 182.20 when taking 4 replicate measurements of this standard. Is your value the same? (b) To be comprehensive you tested the same sample (not the NIST standard) numerous times using your method and the "accepted" method for measuring cholesterol. (c) You do not want to give critics an opportunity; there are many at the FDA. You compared the results you get to the accepted method when measuring many different samples. Using the data obtained below, compare your method of analysis to the accepted method for measuring cholesterol. Do your results agree with the accepted method? $$ \begin{array}{ccc} \text { Sample # } & \text { Your Method (mg/dL) } & \text { Accepted Method (mg/dL) } \\ 1 & 174.60 & 174.93 \\ 2 & 142.32 & 142.81 \\ 3 & 210.67 & 209.06 \\ 4 & 188.32 & 187.92 \\ 5 & 112.41 & 112.37 \end{array} $$

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