# Golden Jackal mandible length

These data are from a collection of specimens in the British Museum of Natural History, London, UK. They show mandible lengths (in mm) for male and female golden jackals (Canis aureus).

Table 1. Mandible lengths for male and female golden jackal.

 Male Female 120 110 107 111 110 107 116 108 114 110 111 105 113 107 117 106 114 111 112 111

You can download the dataset as a CSV file using this link: jackal-mandible. Alternatively, you might copy the table to the clipboard and paste into a spreadsheet.

## Usage

You can use these data to practice/illustrate various topics:

• Summary statistics (e.g. mean, standard deviation).
• Differences hypothesis test (e.g. Student’s t-test).
• Graphics (e.g. box-whisker plot).

## Keywords

Mammal, Jackal, parametric, mean, differences, t-test, graphics, boxplot.

## Examples

The following examples will give you a few ideas about how you might explore these data.

### Summary Statistics

The data are in two separate samples and you can summarise these using the “usual” statistics. This assumes the data are parametric, which is something you can explore.

Table 2. Summary statistics for golden jackal mandible lengths.

 Male Female Sum 1134 1086 Count 10 10 Mean 113.4 108.6 Std.Dev 3.72 2.27

### Student’s T-test

Since the data are morphological measurements we’d expect them to be normally distributed. You could check this by making a histogram or carrying out a test of normality (such as a Shapiro-Wilk test). A suitable test of differences between the samples is the Student’s t-test.

If you conducted a t-test you’d get results along these lines: t = 3.48, df = 18, p < 0.01. This shows that, for these samples, mandible lengths for male golden jackal are larger than female.

### Graphics

There are various graphical methods that could be used to visualise these data, the box-whisker plot is the most informative. The boxplot shows median values as a stripe, inter-quartile ranges as a box, and the extreme range as the whiskers.

You might also consider a bar chart (Excel calls this a column chart). However, you would also need to add error bars to show the variability. Suitable measures would be: standard deviation, standard error or confidence interval.

Figure 1. jackal-mandible-boxplot.png Mandible lengths of golden jackals.

## References

Higham, C.F.W., Kijngam, A., and Manly, B.F.J. (1980) An analysis of prehistoric canid remains from Thailand. Journal of Archaeological Science 7:149-165.

Manly, B.F.J. (2007) Randomization, bootstrap and Monte Carlo methods in biology. Third Edition. Chapman & Hall CRC, Boca Raton.