Abstract

Yeast are tiny, live, single-celled fungi that are crucial to the process of making dough. They lie dormant until activated by warm liquid. Once activated, the yeast feeds on the sugars in the dough, and produces carbon dioxide that makes the dough rise.

Here, we can see yeast cells multiplying by budding:

It is possible that different dough recipes that contain different amounts of ingredients such as sugar and milk could have different yeast activation times. In this report, we will analyze a data frame of yeast activation time for four different dough recipes. From this data, we will determine if yeast activation times differ for the different recipes.

Dough before and after rising from yeast activation.

Data

This data frame shows the activation times (in seconds) for different dough trials.
Yeast Activation Time Summary
Activation.Times Recipe
575 A
395 A
280 B
120 B
720 C
554 C
200 D
135 D
525 A
450 A
175 B
210 B
700 C
650 C
250 D
150 D

Research Question

Do different dough recipes effect the activation time of yeast?

Summary

In this data set, dough recipes were tested to see if different recipes effect the activation time of yeast, by measuring how many seconds it took for the different doughs to rise to the top of the bowl.

From this plot, we can see that four different recipes were tested (A, B, C, and D), and each recipe was tested four times.

We can also make a summary table, and from this we can see that the mean activation time for the yeast was 380.6 seconds, with some trials taking much less time, and some taking much more.

Yeast Activation Times Summary
Activation.Times Recipe
Min. :120.0 A:4
1st Qu.:193.8 B:4
Median :337.5 C:4
Mean :380.6 D:4
3rd Qu.:559.2 NA
Max. :720.0 NA

Exploring the Data

To compare the distributions of yeast activation times, we can use boxplots.

From this boxplot, we can see that some recipes took much less time then others for the yeast to fully activate.

Analysis

To analyze this data, we can perform a one-way ANOVA analysis to test the null hypothesis that yeast activation time is the same for all recipes (variable Recipe, 4 levels):

##             Df Sum Sq Mean Sq F value   Pr(>F)    
## Recipe       3 638968  212989   44.74 8.64e-07 ***
## Residuals   12  57128    4761                     
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

We see that the value of the F statistic is large (44.7). The numerator degree of freedom of the test distribution is 3 (because we have 4 groups of methods) and the denominator degree of freedom of the test distribution is 12 (=16-4).

Conclusion

The p-value of the F-test is extremely low (pval: 8.639741e-07), far below 0.05. We reject the null hypothesis that activation times are the same across all methods

From this test, we know that different dough recipes will effect the rate at which yeast activates.

Dough risen from yeast activation.