14. UKURAN PEMUSATAN/
MEASURES OF CENTRAL TENDENCY
( common averages: mean, median, mode)
mean: regular meaning of "average“
median: middle value
mode: most often
15. For a probability distribution, the mean is also called the
expected value of the random variable. For a data sample, the mean is
also called the average
16. Student: Which one is better: mean,
median or mode?
• Mentor: It depends on your goals. I can
give you some examples to show you
why. Consider a company that has nine
employees with salaries of 35,000 a year,
and their supervisor makes 150,000 a
year. If you want to describe the typical
salary in the company, which statistics will
you use?
• Student: I will use mode (35,000),
because it tells what salary most people
get.
17. • Mentor: What if you are a recruiting officer for
the company that wants to make a good
impression on a prospective employee?
• Student: The mean is (35,000*9 + 150,000)/10 =
46,500 I would probably say: "The average
salary in our company is 46,500" using mean.
• Mentor: In each case, you have to decide for
yourself which statistics to use.
• Student: It also helps to know which ones other
people are using!
23. • The oldest person in Mathsminster is 90.
The youngest person is 15.
• The median age of the residents is 44, the
lower quartile is 25, and the upper quartile
is 67.
• Represent this information with a box-and-
whisker plot.
24. Ukuran pemusatan yang lain:
1. Simpangan rata-rata
• Simpangan rata-rata
n
∑ xi − x
SR = i =1
n
