Table 1.

Top 20 keywords for question 1 using TF and TF–IDF analyses

Rank	TFa		TF–IDFb
	Keywords	Frequency	Keywords	TF–IDF
1	Physician	578	Patient	55
2	Satisfaction	288	Medical Practice	39
3	Thought	242	Person	38
4	Job	219	Self	38
5	Patient	170	Need	37
6	Medical	170	Time	35
7	Improvement	152	Society	35
8	Work	137	Work	33
9	Medical Practice	105	Method	33
10	Time	97	Life	27
11	Person	89	Problem	26
12	Society	74	Environment	24
13	Self	59	South Korea	24
14	Need	54	Importance	24
15	South Korea	53	Medical Fees	24
16	Department	52	Medical School	23
17	Problem	51	Result	23
18	Method	47	Hospital	22
19	Environment	45	Process	22
20	Life	42	Study	21

^aTF Term frequency

^bTF–IDF Term frequency–inverse document frequency