UKURAN PEMUSATAN/ MEASURES OF CENTRAL TENDENCY( common averages: mean, median, mode) mean: regular meaning of "average“ median: middle value mode: most often
For a probability distribution, the mean is also called theexpected value of the random variable. For a data sample, the mean is also called the average
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.
• 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!
• 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.
Ukuran pemusatan yang lain: 1. Simpangan rata-rata• Simpangan rata-rata n ∑ xi − x SR = i =1 n
2. Ragam (Variance) (x ) n ∑ 2 i −xs = 2 i =1 n