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Chapter 5: Q4P (page 114)

Distinguish raw data, treated data, and results.

Short Answer

Expert verified
  • Raw data are the unprocessed measurements collected from the specimens being studied.
  • Treated data are the concentrations found from the raw data with the use of calibration procedures.
  • Results are the reported data after the application of various statistical analyses to the treated data.

Step by step solution

01

Raw data, Treated data and results

Raw data:

Raw data are data's which can be measured directly.

Examples such as peak area in a chromatogram or volume from a burette.

Treated data:

When the raw data applied using calibration methods the resultant data obtained is known as treated data.

Results:

Results are ultimate reports that we report after the application of statistical methods (mean, standard deviation) to the Treated data.

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Most popular questions from this chapter

Blind Samples: Interpreting Statistics-- The U.S. Department of Agriculture provided homogenized beef baby food samples to three labs for analysis.4Results from the labs agreed well for protein, fat, zinc, riboflavin, and palmitic acid. Results for iron were questionable: Lab A, 1.59±0.14(13); Lab B, 1.65±0.56 (8); Lab C, 2.68±0.78(3) mg/100 g . Uncertainty is the standard deviation, with the number of replicate analyses in parentheses. Use two separate t tests to compare results from Lab Cwith those from Lab A and Lab B at the 95 % confidence level. Comment on the sensibility of the t test results and offer your own conclusions.

Control chart. A laboratory monitoring perchlorate (CIO-4)in urine measured quality control samples made from synthetic urine spiked withCIO-4. The graph in Box5-2shows consecutive quality control measurements. Are any troubleshooting conditions from Box 5-2 observed in these data?

Correlation coefficient and Excel graphing. Synthetic

data are given below for a calibration curve in which random Gaussian

noise with a standard deviation ofwas superimposed on

y values for the equationy=26.4x+1.37

. This exercise shows that

a high value ofR2

does not guarantee that data quality is excellent.

(a)Enter concentration in column A and signal in column B of a

spreadsheet. Prepare an XY Scatter chart of signal versus concentration

without a line as described in Section2-11

. Use LINEST

(Section 4-7) to find the least-squares parameters includingR2

.

(b)Now insert the Trendline by following instructions on page 88.

In the Options window used to select the Trendline, select Display

Equation and Display R-Squared. Verify that Trendline and LINEST

give identical results.

(c)Add 95%confidence interval y error bars following the instructions

at the end of Section 4-9. The95%

confidence interval is 6tsy,

wheresy

comes from LINEST and Student’s tcomes from Table 4-4

for95%confidence and11-2=9

degrees of freedom. Also, compute

t with the statement "=TINV(0.05,9)".

Internal standard graph -- Data are shown below for chromatographic analysis of naphthalene (C10H8), using deuterated naphthalene (C10D8, in which D is the isotope 2H) as an internal standard. The two compounds emerge from the column at almost identical times and are measured by a mass spectrometer.

(a) Using a spreadsheet such asFigure 4-15, prepare a graph of Equation 5-12 showing peak area ratio(C10H8/C10D8)versus concentration ratio role="math" localid="1663559632352" ([C10H8]/C10D8) . Find the least-squares slope and intercept and their standard uncertainties. What is the theoretical value of the intercept? Is the observed value of the intercept within experimental uncertainty of the theoretical value?

(b) Find the quotientrole="math" localid="1663559638520" [C10H8]/[C10D8]for an unknown whose peak area ratio (C10H8/C10D8) is 0.652. Find the standard uncertainty for the peak area ratio.

(c) Here is why we try not to use 3-point calibration curves. For n = 3 data points, there is n - 2 = 1 degree of freedom, because 2 degrees of freedom are lost in computing the slope and intercept. Find the value of Student's for confidence and 1 degree of freedom. From the standard uncertainty in (b), compute the 95 % confidence interval for the quotient[C10H8]/[C10D8] . What is the percent relative uncertainty in the quotient[C10H8]/[C10D8]? Why do we avoid 3-point calibration curves?

Internal standard. A solution was prepared by mixing 5.00mLof unknown elementXwith2.00mLof solution containingrole="math" localid="1654777035083" 4.13μgof standard elementSper millilitre, and diluting to10.0mL. The signal ratio in atomic absorption spectrometry was (signal fromX)/ (signal fromS)=0.808. In a separate experiment, with equal concentrations ofXandS, (signal fromX)/signal fromS)=1.31. Find the concentration ofXin the unknown.
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