Question

Suppose you want to estimate the percentage of videos on
YouTube that are cat videos. It is impossible for you to watch all videos on YouTube so you
use a random video picker to select 1000 videos for you. You nd that 2% of these videos are
cat videos.Determine which of the following is an observation, a variable, a sample statistic,
or a population parameter.
(a) Percentage of all videos on YouTube that are cat videos.
(b) 2%.
(c) A video in your sample.
(d) Whether or not a video is a cat video.

Answer 1

(a)

Percentage of all videos on YouTube that are cat videos is our required parameter whose value is to be estimated using sample observations. So, this is a population parameter.

(b)

From the sample data we find that 2% of our sampled videos are cat videos. So, this is a sample statistic.

(c)

We observed all the 1000 sampled videos. Here each of the 1000 sampled videos are sample units which we observe to estimate some value (percentage of all videos on YouTube that are cat videos). So, a video in our sample is an observation.

(d)

To estimate percentage of all videos on YouTube that are cat videos, we draw a sample and calculate percentage of videos in the sample that are cat videos. Here being a cat video is a variable which takes any of values 'YES' and 'NO'. Hence, whether or not a video is a cat video is a variable.