Robertson Method - Practical Report PDF

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Practical Report...

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School of Health Sciences

Assignment Cover Sheet I fy o ua r er e q u i r e dt os u b mi ty o ura s s i g n me n two r kvi aap a p e rs u b mi s s i o n, t h e ny ou mu s ts u b mi tac o p yo ft h i sc o v e rs h e e t St u d e n tI Dn umb e r :4 4 6 35 4 Fa mi l yNa me :Ro b e r t s o n

Gi v e nNa me :J o s i e

Un i tCo d e :CXA25 1 Un i tNa me :Cl i n i c a lCh e mi s t r y1 As s i g n me n tTi t l e : Pr a c t i c a lRe p o r t 1–Me t h o dCo mp a r i s on( R&DOn l y ) Wo r dCo u n t :5 7 6 Ide c l a r et ha tal lma t e r i al i nt hi sa s s i g nme nti smyo wnwo r ke x c e ptwhe r et he r ei s c l e a ra c kno wl e dg e me ntorr e f e r e nc et ot hewo r ko fot he r sa ndIha v ec o mpl i e da nd ag r e e dt ot heUni v e r s i t ys t a t e me nto nPl a g i a r i s ma ndAc ade mi cI nt e gr i t yo nt he Uni v e r s i t ywe bs i t ea tht t p: / / www. ut a s . e du. a u/ pl a g i ar i s ma ndi nt heuni to ut l i ne .

Si g ne d:J .Ro b e r t s o n

Da t e :2 4 / 0 8 / 2 01 8

Statement on Plagiarism and Academic Integrity Pl a g i a r i s mi saf or mo fc h e a t i n g . I ti st a ki n ga n dus i n gs o me on ee l s e ' st h ou g h t s ,wr i t i n g so ri n v e n t i on sa n d r e pr e s e nt i n gt he ma sy o u ro wn , f ore x a mp l e :  u s i n ga na u t h o r ' swo r d swi t h o utp ut t i n gt he mi nq u o t a t i o nma r k sa ndc i t i n gt hes o ur c e ;  u s i n ga na u t h o r ' si de a swi t ho u tp r o p e ra c kn o wl e d g me nta n dc i t a t i on ;o r  c o p y i n ga n o t h e rs t u de n t ' swo r k . I fy o uh a v ea n ydo u bt sa b o uth o wt or e f e rt ot h ewor ko fo t he r si ny o ura s s i g n me n t s ,p l e a s ec o ns u l ty o u r l e c t ur e rort ut o rf o rr e l e v a ntr e f e r e nc i n ggu i de l i n e s , a ndt h ea c a de mi ci n t e gr i t yr e s o u r c e so nt hewe ba t h t t p : / / www. a c a de mi c i nt e g r i t y . u t a s . e d u . a u Thei n t e nt i o n a lc op yi n go fs o me on ee l s e ’ swo r ka son e ’ so wni sas e r i ou so ffe n c epu n i s ha b l eb ype n a l t i e s t ha tma yr a n g ef r o mafineord e du c t i on / c a n c e l l a t i o nofma r ksa n d, i nt h emo s ts e r i o u so fc a s e s ,t o e x c l u s i o nf r o maun i t ,ac o ur s eort h eUni v e r s i t y . De t a i l sofp e na l t i e st h a tc a nb ei mp os e da r ea v a i l a bl ei n t heOr d i n a nc eofSt u d e ntDi s c i pl i n e–Pa r t3Ac a de mi cMi s c on d u c t ,s e e h t t p : / / www. u t a s . e d u . a u / un i v e r s i t y c o u nc i l / l e g i s l a t i on / o r d9 . p d f TheUn i v e r s i t yr e s e r v e st her i gh tt os u bmi ta s s i g n me n t st opl a g i a r i s md e t e c t i ons o f t wa r e , a ndmi g h tt h e n r e t a i nac o p yo ft hea s s i g nme n to ni t sda t a b a s ef o rt hepu r p os eo ff u t u r ep l a g i a r i s mc h e c ki n g . Pl e a s er e f e rt ot h eUni tOu t l i n ef o ramo r ed e t a i l e ds t a t e me ntonpl a gi a r i s m.

1

Contents; Summary

pg 2

Results

pg 3-7

Discussion

pg 8

Summary; For this method comparison study, two different reagents were tested for the same analyte. The reagents were Bromocresol Green (BCG) and Bromocresol P (BCP). The analyte of interest was albumin. The BCG method required 20µL of sample and 6.0mL or reagent, tubes were incubated at room temperature for 2 minutes, and the absorbance was measured at 630nm. The BCP method required 20µL of sample and 3.0mL of reagent, tubes were incubated at room temperature for two minutes, and the absorbance was measured at 600nm. Each student ran a standard (in duplicate), a set of controls (1 and 2) and 5 samples, seen in Table 1. By combining the class data, a duplicate test for each sample was presented for the samples, seen in Table 3. The class data set was analysed through MedCalc to produce the follwing data, Tables 1-4 and Figures 1-3.

2

Results; Table 1; Individual Results (Student 446354)

Test Standard 1 Standard 2 QC 1 QC 2 Sample 28 Sample 36 Sample 39 Sample 45 Sample 51

Absorbance 0.302 0.326 0.340 0.198 0.346 0.492 0.141 0.155 0.390

BCG Assay Concentration (g/L)

Absorbance 0.350 0.351 0.343 0.215 0.383 0.479 0.187 0.194 0.411

40 43 25 44 63 18 20 50

BCP Assay Concentration (g/L) 40 39 24 40 55 21 22 47

All 4 Quality Control results (QC 1 and 2 for each reagent) were within 2 standard deviations of the mean. See Table 2. Table 2; Quality Control Ranges and Results

QC 1; My Result – 43 QC 2; My Result – 25

QC 1; My Result – 39 QC 2; My Result – 24

BCG Reagent - 1 sd Mean + 1 sd

- 3 sd

- 2 sd

36

39

42

45

21

23

25

27

- 3 sd

- 2 sd

27

31

34

37

18

20

22

24

+ 2 sd

+ 3 sd

48

51

54

29

31

33

+ 2 sd

+ 3 sd

40

43

46

26

28

30

BCP Reagent - 1 sd Mean + 1 sd

Table 3; Group Results (Thursday Morning Class) Albumin BCG Method - Reference Sample 1 2 3 4 5 6 7 8 9 10 11^ 12 13

BCG1 28 38 40 50 60 33 30 63 24 38 9 26 46

BCG2 20 40 41 48 63 34 31 54 20 37 11 28 44

BCG Mean 24 39 41 49 61 34 31 59 22 37 10 27 45

Albumin BCP Method - Test BCP1 29 39 42 47 57 34 30 52 24 38 11 27 46

BCP2 20 40 41 48 56 32 31 53 20 36 28 43

BCG Mean 25 40 42 48 57 33 31 53 22 37 11 28 45

3

14 15* 16 17 18^ 19^ 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47^ 48 49^ 50 51 52 53 54^ 55^ 56 57 58* 59 60

40 44 62 52 26 21 7 47 40 16 36 16 29 31 44 45 31 50 19 37 24 53 63 35 34 18 34 49 15 49 13 20 33 34 44 59 44 50 47 24 62 46 15 22 60 47 54

43 32 63 50

10 49 42 22 37 17 33 39 40 44 36 55 16 43 21 52 59 34 38 16 42 50 13 50 15 19 30 43 45 43 44 28

15 24 57 49 51

42 38 63 51 26 21 9 48 41 19 36 17 31 35 42 44 34 53 18 40 23 53 61 34 36 17 38 50 14 50 14 20 32 34 44 59 44 47 46 26 62 46 15 23 59 48 53

41 50 58 51 33 28 10 44 41 25 35 20 35 36 40 44 34 52 19 37 25 49 55 37 40 21 39 47 16 50 17 22 33 36 44 53 42 47 46 29 59 44 18 27 52 49 52

43 44 57 50 25 19 12 48 40 27 38 18 34 39 40 44 32 50 15 37 27 49 57 35 34 19 35 48 17 50 16 22 29 42 43 50 43 45 43 30 57 45 18 23 38 45 51

42 47 58 51 29 24 11 46 41 26 37 19 35 37 40 44 33 51 17 37 26 49 56 36 37 20 37 47 17 50 17 22 31 39 44 51 42 46 45 30 58 45 18 25 45 47 52

* Excluded due to the presence of outliers. ^ Excluded do to incomplete data set.

4

Figure 1; Residual Plot Method Comparison Residual Plot 8

The outliers are identified to be samples 15 and 58 (circled), as there was a difference greater than 5g/L between the regression line and these data points. These were excluded from the data set for all further testing.

6 BCP (Mean)

4 2 0 -2 -4 -6 -8 0

10

20

30 40 BCG (Mean)

50

60

70

Figure 2; Deming Regression Scatterplot

Deming Regression Plot 70

y = 4.971 + 0.864 x n = 51

60 BCP Mean

50 40 30 20 10 0 0

10

20

30

40

50

60

70

BCG Mean

5

Table 4; Deming Regression Summary Table Table 4a; Deming Regression Statistics Method X

BCG1

Method Y

BCG2 BCP1 BCP2 Method X Y

Mean 36.7157 36.6961

Sample size Variance ratio

Coefficient of variation (%) 7.01 4.94 51 2.0149

Table 4b; Deming Regression Equation y = 4.9705 + 0.8641 x Parameter Coefficient 4.9705 Intercept Slope 0.8641

Std. Error 0.6685 0.01659

95% CI 3.6279 to 6.3132 0.8308 to 0.8974

Pearson correlation coefficient 95% Confidence interval

0.9924 0.9867 to 0.9957

Figure 3; Bland and Altman Plot

Bland and Altman Plot 15

BCG - BCP

10 +1.96 SD 6.9

5

Mean 0.1

0 -5

-1.96 SD -6.7

-10 10

20

30

40

50

60

70

Mean of BCG and BCP

6

Systematic Error Using Deming Regression Equation (Y = 0.9641x + 4.9705) and the following critical decision points; Xc = 2.0, Xc = 3.5 and Xc = 5.2. Yc at Xc = 2.0 Yc

= (0.8641 x 2.0) + 4.9705 = 6.6987

SE

= Yc – Xc = 6.70 – 2.0 = 4.70

Yc at Xc = 3.5 Yc

= (0.8641 x 3.5) + 4.9705

= 7.99485 SE

= Yc – Xc = 8.00 – 3.5 = 4.50

Yc at Xc = 5.2 Yc

= (0.8641 x 5.2) + 4.9705 = 9.46382

SE

= Yc – Xc = 9.46 – 5.2 = 4.26

7

Discussion; Of the 60 test results obtained, seven were not used in the analysis as they were missing their duplicate (therefore that sample was defined as an incomplete data set), denoted in Table 3 by (^). There were 6 samples from the BCG Test (18, 19, 47, 49, 54 and 55) and 1 sample from the BCP Test (11). On visual analysis of the residual plot, 2 samples were excluded from the data set as their residual value (the difference between the actual result t=and that predicted by the linear regression equation) exceeded 5. These samples were 15 and 58., which are highlighted on the residual plot and denoted in Table 3 by (*) On visual analysis of the Deming Regression Scatter Plot (Figure 2), the data points are all closely gathered around the regression line (in red). This is an initial indicator that the regression line is well fitting, and hence, the methods compare well. Analysing the Deming Regression Statistics Tables (Tables 4a and 4B), gives a stronger indication of how well the regression fits the data, and hence, how well the methods compare. The slope of the linear regression is a measurement of the proportional change in value from one method to another. As this number (0.8641) is very close to one, it indicates that the regression fits and the methods compare well. Upon analysis of the systematic error of the methods, at designated critical decision points, a trend can be established. As the value for X increases, the value calculated for SE decreases slightly. This means that the higher the X value, the lower the systematic error, as the methods’ results are trending closer as the concentration of analyte increases.

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