Include Minitab output if appropriate. Did you wash your hands with soap before
ID: 2925750 • Letter: I
Question
Include Minitab output if appropriate. Did you wash your hands with soap before eating? You've undoubtedly been asked that question a few times in your life. Mom knows that washing with soap eliminates most of the germs you've managed to collect on your hands. Or does it? A student decided to investigate just how effective washing with soap is in eliminating bacteria. To do this she tested four different methods-washing with water only, washing with regular soap, washing with antibacterial soap (ABS), and spraying hands with antibacterial spray (AS) (containing 65% ethanol as an active ingredient). Her experiment consisted of one experimental factor, the washing Method, at four levels. She suspected that the number of bacteria on her hands before washing might vary considerably from day to day. To help even out the effects of those changes, she generated random numbers to determine the order of the four treatments. Each morning she washed her hands according to the treatment randomly chosen. Then she placed her right hand on a sterile media plate designed to encourage bacteria growth. She incubated each plate for 2 days at 36°C, after which she counted the bacteria colonies. She replicated this procedure 8 times for each of the four treatments. Below is the data. Alcohol AB Soap SoapWater 51 70 84 51 110 67 119 108 207 102 74 135 102 124 105 139 170 164 19 18 58 50 82 17 73 119 20 95 (a) Enter the data in a Minitab Worksheet-save the file as bacteriamtw. (b) Perform a 4C's analysis to determine if a difference exists in the number of bacteria colonies among the four different treatments orm a Bonferroni and Tukey multiple comparison procedure to identify which pairs of treatment are significantly different. Do these procedures give the same results? Use Dunnet's procedure with Soap as the control group, to compare the other three methods to regular soap and water handwashing. Give the conclusions of that procedureExplanation / Answer
One-way ANOVA: Alcohol, AB Soap, Soap, Water
Method
Null hypothesis All means are equal
Alternative hypothesis At least one mean is different
Significance level = 0.05
Equal variances were assumed for the analysis.
Factor Information
Factor Levels Values
Factor 4 Alcohol, AB Soap, Soap, Water
Analysis of Variance
Source DF Adj SS Adj MS F-Value P-Value
Factor 3 29882 9961 7.06 0.001
Error 28 39484 1410
Total 31 69366
Model Summary
S R-sq R-sq(adj) R-sq(pred)
37.5519 43.08% 36.98% 25.65%
Means
Factor N Mean StDev 95% CI
Alcohol 8 37.50 26.56 (10.30, 64.70)
AB Soap 8 92.5 42.0 ( 65.3, 119.7)
Soap 8 106.0 47.0 ( 78.8, 133.2)
Water 8 117.0 31.1 ( 89.8, 144.2)
Pooled StDev = 37.5519
Tukey Pairwise Comparisons
Grouping Information Using the Tukey Method and 95% Confidence
Factor N Mean Grouping
Water 8 117.0 A
Soap 8 106.0 A
AB Soap 8 92.5 A
Alcohol 8 37.50 B
Means that do not share a letter are significantly different.
Tukey Simultaneous 95% CIs
Fisher Pairwise Comparisons
Grouping Information Using the Fisher LSD Method and 95% Confidence
Factor N Mean Grouping
Water 8 117.0 A
Soap 8 106.0 A
AB Soap 8 92.5 A
Alcohol 8 37.50 B
Means that do not share a letter are significantly different.
Yes Both procedures gives same result.
Dunnett Multiple Comparisons with a Control
Grouping Information Using the Dunnett Method and 95% Confidence
Factor N Mean Grouping
Alcohol (control) 8 37.50 A
Water 8 117.0
Soap 8 106.0
AB Soap 8 92.5