The Brown Bear Enrichment Study
Problem:
Is there a significant difference between the mean interaction time with natural enrichment items, and the mean interaction time with unnatural enrichment items?
Subjects
(Two male Brown Bears at the Columbus Zoo)
Brutus
Buckeye
Hypothesis:
The mean interaction time between the brown bears and their enrichment
is higher on days when natural enrichment is given, than on days when
unnatural enrichment is given.
Statistical Test:
The statistical tests used were a t-test of independent sample means, and a f-test for variance. The t-test will be run for the means of the interaction time with natural enrichment, and the interaction time with unnatural enrichment. The confidence level for the study was 95%.
Abstract:
The brown bear staff at the Columbus Zoo and Aquarium is trying to determine whether the two male brown bears, Brutus and Buckeye, spend more time with natural, or unnatural enrichment. The hypothesis formed was that the brown bear interaction with enrichment is higher on days when natural enrichment is presented, than on days when unnatural enrichment is presented. At this time the results for this study are conclusive, and determined that the Brown Bears, Brutus and Buckeye, interacted more with enrichment on days when natural enrichment was presented, than on days when unnatural enrichment was presented.
Movies:
Results:
The purpose of this study was to determine if
there was a significant difference in the mean interaction time with
natural enrichment, and the mean interaction time with unnatural enrichment.
The hypotheses that were tested stated that the mean interaction time
with enrichment was higher on days when natural enrichment was presented,
than on days when unnatural enrichment was presented.
The results of the f test for comparing two sample variances were found to be significant, which determines that a significant dispersion existed between sample (1), and sample (2). The results of the t test unequal variance for two independent sample means were found to be statistically significant, and therefore, the null hypothesis is rejected in favor of the alternative hypothesis, which states that the mean interaction time between the brown bears and their enrichment is higher on days when natural enrichment is given.
T
Figure 1: Comparison of variances
This study was conducted at an alpha level of p= 0.05. Figure 1 shows that there is a significant difference between the two variances of the interaction time with natural enrichment, and the interaction time with unnatural enrichment.
Table 1: Results of f test for variances
| Variable 1 | Variable 2 | |
| Mean |
65.56667 | 24.5 |
| Variance | 1666.185 | 430.259 |
Observations |
30 | 28 |
| Hypothesized Mean Difference | 0 | |
| F Stat | 3.87251 |
|
F Critical one-tail |
2.19 |
Summary
The results of the f test were found to be statistically significant,
which determined that a significant dispersion existed between sample
(1), and sample (2).
Figure 2: Difference Between the Sample Means
aThis study was conducted at an alpha level of p= 0.05. Figure 2 shows that there is a significant difference between the mean calculated interaction time with each type of enrichment. Figure 2 clearly demonstrated that interaction time with natural enrichment is greater than unnatural enrichment.
Table 2: Results of t test for sample means: assuming unequal variances
| Variable 1 | Variable 2 | |
| Mean | 65.56667 | 24.5 |
| Variance | 1666.185 |
430.259 |
| Observations | 30 | 28 |
| Hypothesized Mean Difference | 0 | |
| t Stat | 4.88 |
|
| t Critical one-tail | 1.680 |
Summary
The results of the t test were found to be statistically significant
and provided evidence necessary to reject the null hypothesis in favor
of the alternative hypothesis, which stated that the mean brown bear
interaction time with enrichment was higher on days when natural enrichment
was presented.
Conclusion:
The conclusion can be drawn that the mean interaction time between the brown bears and their enrichment is higher on days when natural enrichment is presented, than on days when unnatural enrichment is given. The conclusion can also be drawn that the variance of natural enrichment is significantly larger than the variance for unnatural enrichment.
Implications:
As a result of the evidence provided in this study, zookeepers should continue presenting the brown bears with natural enrichment items such as deer antlers, pheasant feathers and pine trees. This will ensure that the brown bears continue to display as much as their natural abilities as possible when guests are present. This study also found that if unnatural enrichment was given, the unnatural enrichment item the bears responded to most was the boomer ball.
Columbus Zoo & Aquarium School: 2006
© 2006 All rights reserved.