What Do the Stats Tell You About the Seaman Roundup?

BLM reported that 162 studs, 187 mares and 48 foals had been gathered, as of 01-09-20, with no animals returned to their home range.

The contractor captured more mares than studs but does that result point to anything unusual or can the difference be attributed to chance?

The sex of the foals was not given so their number should be omitted from the total.

The expected proportion of mares and studs is .50 (50%), but that is a property of an indefinitely large number of horses.

The observed proportions are .464 for studs and .536 for mares, with n = 349.

The range of variation attributable to chance can be computed from basic statistical formulas, where p-bar = .50 and n = 349.  The observed proportions fall within the calculated limits of .420 and .580, so these results don’t point to anything unusual.

That doesn’t mean the contractor wasn’t asked to alter the herd in some manner, such as skewing the sex ratio of the herd in favor of studs, only that there’s no evidence of that in these data.

Bachelor bands may blend with family bands in a helicopter roundup, resulting in a more-or-less even distribution of males and females in the traps.

Any sex ratio skewing would have to be accomplished by selective return.

RELATED: Seaman Roundup Continues.

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