Analysis of the Goggles data, using Attractiveness as the response variable and Alcohol as the single grouping factor.

Prepared by BrailleR

Group summaries

Level Mean Standard deviation n Standard error
None 63.7500 8.465617 16 2.116404
2 Pints 64.6875 9.911063 16 2.477766
4 Pints 46.5625 14.343262 16 3.585816

The ratio of the largest group standard deviation to the smallest is 1.69

Comparative boxplots

Comparative boxplots

 This graph has 3 boxplots printed vertically
 with the title: 
 "" appears on the x-axis.
 "" appears on the y-axis.
 Tick marks for the y-axis are at: 20, 30, 40, 50, 60, 70, and 80 
 Group None has 16 values.
 There are no outliers marked for this group 
 The whiskers extend to 50 and 80 from the ends of the box, 
 which are at 57.5 and 70 
 The median, 62.5 is 40 % from the lower end of the box to the upper end.
 The upper whisker is 1.33 times the length of the lower whisker.
 Group 2 Pints has 16 values.
 There are no outliers marked for this group 
 The whiskers extend to 45 and 85 from the ends of the box, 
 which are at 60 and 70 
 The median, 65 is 50 % from the lower end of the box to the upper end.
 The upper whisker is 1 times the length of the lower whisker.
 Group 4 Pints has 16 values.
 There are no outliers marked for this group 
 The whiskers extend to 20 and 70 from the ends of the box, 
 which are at 32.5 and 55 
 The median, 50 is 78 % from the lower end of the box to the upper end.
 The upper whisker is 1.2 times the length of the lower whisker.

Comparative dotplots

Warning in dotplot.formula(attractiveness ~ alcohol, xlab = "Attractiveness", :
The dotplot command is a wrapper for stripchart, and is not a base R function.

Comparative dotplots

This graph has 48 dotplots printed horizontally
with the title: 
"" appears on the x-axis.
"" appears on the y-axis.
Tick marks for the x-axis are at: 20, 30, 40, 50, 60, 70, and 80 
the data that range from 20 to 85 has been broken into 6 bins.
The counts are:
None: 0 0 1 0 0 0 
2 Pints: 0 0 1 0 0 0 
4 Pints: 1 0 0 0 0 0 
NA: 0 0 0 1 0 0 
NA: 0 0 1 0 0 0 
NA: 1 0 0 0 0 0 
NA: 0 0 0 1 0 0 
NA: 0 0 0 1 0 0 
NA: 1 0 0 0 0 0 
NA: 0 0 0 1 0 0 
NA: 0 0 0 1 0 0 
NA: 1 0 0 0 0 0 
NA: 0 0 0 1 0 0 
NA: 0 0 0 1 0 0 
NA: 0 1 0 0 0 0 
NA: 0 0 0 1 0 0 
NA: 0 0 0 1 0 0 
NA: 0 1 0 0 0 0 
NA: 0 0 0 1 0 0 
NA: 0 0 0 1 0 0 
NA: 0 0 1 0 0 0 
NA: 0 0 0 1 0 0 
NA: 0 0 0 0 1 0 
NA: 0 0 1 0 0 0 
NA: 0 0 0 0 1 0 
NA: 0 0 0 0 1 0 
NA: 0 0 1 0 0 0 
NA: 0 0 0 0 1 0 
NA: 0 0 0 0 1 0 
NA: 0 0 0 1 0 0 
NA: 0 0 0 0 1 0 
NA: 0 0 0 0 1 0 
NA: 0 0 0 1 0 0 
NA: 0 0 0 0 1 0 
NA: 0 0 0 0 1 0 
NA: 0 0 0 1 0 0 
NA: 0 0 0 0 1 0 
NA: 0 0 0 0 1 0 
NA: 0 0 0 1 0 0 
NA: 0 0 0 0 0 1 
NA: 0 0 0 0 1 0 
NA: 0 0 0 1 0 0 
NA: 0 0 0 0 0 1 
NA: 0 0 0 0 0 1 
NA: 0 0 0 0 1 0 
NA: 0 0 0 0 0 1 
NA: 0 0 0 0 0 1 
NA: 0 0 0 0 1 0 

One-way Analysis of Variance


The p value for alcohol is 0

The ratios of the group standard deviations to the overall standard deviation 
 (groups ordered by increasing mean) are:
 0.76 0.89 1.28

            Df Sum Sq Mean Sq F value   Pr(>F)    
alcohol      2   3332  1666.1   13.31 2.88e-05 ***
Residuals   45   5634   125.2                     
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual analysis

Tests for homogeneity of Variance


    Bartlett test of homogeneity of variances

data:  attractiveness by alcohol
Bartlett's K-squared = 4.4295, df = 2, p-value = 0.1092

    Fligner-Killeen test of homogeneity of variances

data:  attractiveness by alcohol
Fligner-Killeen:med chi-squared = 4.3876, df = 2, p-value = 0.1115

Tukey Honestly Significant Difference test

For term alcohol the comparisons which are significant at 5% are:
None and 4 Pints with a difference of 17.19 and P-value of 2e-04 
2 Pints and 4 Pints with a difference of 18.12 and P-value of 1e-04 
  Tukey multiple comparisons of means
    95% family-wise confidence level
    factor levels have been ordered

Fit: aov(formula = attractiveness ~ alcohol, data = goggles)

$alcohol
                   diff       lwr      upr     p adj
None-4 Pints    17.1875  7.599346 26.77565 0.0002283
2 Pints-4 Pints 18.1250  8.536846 27.71315 0.0001067
2 Pints-None     0.9375 -8.650654 10.52565 0.9695381

Plot of Tukey HSD