However, when the number of objects to track is unknown or varies over time, tracking hypothesis with different Numbers of objects have to be compared.

而当目标数未知或随时间变化时，需要对不同目标数的跟踪进行比较。

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DeArthur, she says, kept stalling, giving her fake or wrong tracking numbers.

FORBES: Robbing the Cradle

Now comes a phenomenon known as the Quantified Self, or self-tracking, which posits a sort of truth in numbers.

FORBES: Magazine Article

In tracking polls, the trend counts as much as or more than today's numbers.

CNN: About the Tracking Polls