• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Effect of Mouthwash on E-Coli Bacteria

Extracts from this document...

Introduction

Interpreting and Evaluating Mann-Whitney U test I have decided that I would like to use the Mann-Whitney U test to interpret and evaluate my data. This is because I would like to compare data sets to see whether the medians from the different brands of mouthwash I investigated were significantly different from one another as I have unmatched data and this would help me to demonstrate their differences clearly. Effect of Mouthwash on E-Coli Bacteria Results For E-Coli Result No. Mouthwash A (mm) Mouthwash B (mm) Mouthwash C (mm) Mouthwash D (mm) 1 2.14 4.65 6.22 1.81 2 1.88 3.86 5.34 1.98 3 2.46 4.39 4.82 2.12 4 2.79 4.29 6.10 1.88 5 2.74 3.35 4.98 2.06 6 2.54 3.23 5.40 1.91 7 2.81 4.12 5.83 2.43 8 1.95 3.54 5.17 1.78 9 2.65 4.16 5.51 1.65 10 2.27 3.48 5.65 1.54 Average 2.423 3.907 5.502 1.916 Average Results Mouthwash A B C D Median (mm) 2.423 3.907 5.502 1.916 Ranking the Data 1) Mouthwash C 2) Mouthwash B 3) Mouthwash A 4) Mouthwash D ? R1 (Mouthwash C) = 55.02 ? R2 (Mouthwash B) = 39.07 ? R3 (Mouthwash A) = 24.23 ? R4 (Mouthwash D) = 19.16 Comparison of Mouthwash A against B: U1 = ( n x n ) + (0.5n ) (n + 1) ...read more.

Middle

- 39.07 = 115.93 U2 = ( n x n ) + (0.5n ) (n + 1) - ? R U1 = (10 x 10) + (0.5[10]) (10 + 1) - 19.16 = 135.84 Smaller Value = 115.93 Critical Value for U = 23 115.93 > 23 Comparison of Mouthwash C against D: U1 = ( n x n ) + (0.5n ) (n + 1) - ? R U1 = (10 x 10) + (0.5[10]) (10 + 1) - 55.02 = 99.98 U2 = ( n x n ) + (0.5n ) (n + 1) - ? R U1 = (10 x 10) + (0.5[10]) (10 + 1) - 19.16 = 135.84 Smaller Value = 99.98 Critical Value for U = 23 99.98 > 23 Effect of Mouthwash on Microccus Liteus Bacteria Result No. Mouthwash A (mm) Mouthwash B (mm) Mouthwash C (mm) Mouthwash D (mm) 1 7.30 5.04 7.86 4.21 2 7.81 6.49 7.73 4.50 3 8.45 6.98 7.62 3.38 4 8.72 5.79 7.36 3.47 5 8.64 6.24 6.89 4.95 6 7.94 5.72 6.56 4.13 7 8.58 5.37 7.34 3.91 8 8.63 5.21 6.71 3.86 9 8.36 6.13 7.25 3.22 10 7.79 5.67 7.17 3.34 Average 8.222 5.864 7.252 3.897 Order of Zone of Clearance of Microbial Decay (Highest to Lowest) ...read more.

Conclusion

+ (0.5n ) (n + 1) - ? R U1 = (10 x 10) + (0.5[10]) (10 + 1) - 39.07 = 115.93 U2 = ( n x n ) + (0.5n ) (n + 1) - ? R U1 = (10 x 10) + (0.5[10]) (10 + 1) - 55.02 = 99.98 Smaller Value = 99.98 Critical Value for U = 23 99.98 > 23 Comparison of Mouthwash B against D: U1 = ( n x n ) + (0.5n ) (n + 1) - ? R U1 = (10 x 10) + (0.5[10]) (10 + 1) - 39.07 = 115.93 U2 = ( n x n ) + (0.5n ) (n + 1) - ? R U1 = (10 x 10) + (0.5[10]) (10 + 1) - 19.16 = 135.84 Smaller Value = 115.93 Critical Value for U = 23 115.93 > 23 Comparison of Mouthwash C against D: U1 = ( n x n ) + (0.5n ) (n + 1) - ? R U1 = (10 x 10) + (0.5[10]) (10 + 1) - 55.02 = 99.98 U2 = ( n x n ) + (0.5n ) (n + 1) - ? R U1 = (10 x 10) + (0.5[10]) (10 + 1) - 19.16 = 135.84 Smaller Value = 99.98 Critical Value for U = 23 99.98 > 23 From the data collected from my statistical test I can see that ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Here's what a teacher thought of this essay


Statistical test only** A worked example of the Mann-Whitney U test that has been calculated well but has not been interpreted at all by the candidate.
The statistic has been used correctly and calculated using the formulae for large sample size. A faster method is available for the small sample size used.
To improve- The real point of carrying out statistical tests is to see if there is true significance in the data collected and then interpret and evaluate the experiment accordingly. This candidate has unfortunately not discussed the meaning of the statistic at all.
If the U value is equal to or less than that in the U value table the null hypothesis can be rejected. The difference in these samples is significant at the 2% level.

Marked by teacher Stevie Fleming 26/07/2013

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Marked by a teacher

    The Effect Of Temperature on the Respiration Of Yeast.

    5 star(s)

    To control this temperature drop I am going to add hot water to the polystyrene cup and also stir the water to mix it up. If the experiment lasts more than 2minutes I am going to shake the test tube to mix the TTC and the yeast as the yeast

  2. The Effect of Concentration on Pectinase Using Apple

    It is now clear that an increase in enzyme concentration brings about an increase in the rate of reaction. However this only happens if there are enough substrate molecules to begin with. If there were plenty of enzyme molecules and not many substrate molecules, then after all the substrate had

  1. Type - 1 Hypersensitivity Reaction

    On the second exposure to egg albumin in the sensitised ileum, there was no contractile response, a reason to this was because the mast cells had already been ruptured, and through the degranulation of the mast cells, the histamine that had been released via the first exposure of the egg

  2. Planning an experiment into the effect of mouthwash on bacteria

    The enzymic reaction is reduced because while the inhibitor is in the active site, no substrate can enter. Substrate molecules compete for the active site so the rate of reaction decreases as the higher the proportion of competitive inhibitor the slower the rate of reaction.

  1. Investigating the effect of temperature on the activity of free and immobilised enzymes.

    Evaluation Although the results obtained from the experiment support my prediction, I was not satisfied with the experiment, as the results obtained were limited as the experiment was only repeated three times. There were a lot of errors, both in the conducting of the experiment, and in the results obtained.

  2. DETERMINING THE WATER POTENTIAL OF A POTATO TUBER CELLS USING THE WEIGHING METHOD.

    It can be said that because Marilyn is a technician and has probably done more than one try to get her results so it is more likely to give perfect results. Furthermore there are results that make the graph look like an anomalous result but it is due to the

  1. Investigation of the effect of adding different concentrations of NaCl to an enzyme-substrate (amylase-starch) ...

    Without the presence of enzymes many reactions in the cell would be too slow to sustain life and many reactions would require very extreme conditions in order to occur; most cells would be destroyed. Most enzymes are globular proteins made up of folded peptide chains.

  2. The investigation to find the effect of glucose concentration on fermentation of yeast.

    at 40 degrees centigrade by means of a water bath. This temperature has been chosen, as it is the optimum temperature for the enzymes to operate at. Beyond this point, although the number of collisions with the active site is increased (the kinetic theory,)

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work