Table 3 Advantages and disadvantages of participating in Internet RCTs

1. flexibility, convenience, ability to control time and place of participation

1a. less flexibility, less interpersonal connectedness and communication,

own time^A

no personal contact^B

convenient^A

can only use email to f/u^C

any time/flexible time to complete^B

less motivation/less rewarding^C

easily accessible^B

no direct feedback^C

no travel/convenient place^B

no interaction between participants^C

no appointments^B

no discussion about how study is going^C

access study from anywhere^B

disjoint - not part of the research^C

flexibility/allows for busy lives /fits into my schedule^B

more personal benefits from conventional research^C

accessible at all times^C

no follow-up possibilities^C

I have the choice to participate/find out about study^C

can not deviate from questions/allow for special circumstances^B

prefer mix of methods^C no one to talk to incase of adverse events^C

1b. difficulty in understanding/being understood

can't ask questions/can't get immediate answers^A

no advice about intervention or outcome reporting^B

mis-interpret/don't understand question/information^B

not enough detail in answers/fixed answers^B

difficult to convey message^C

unable to clarify/provide/ask for further details^C

computer literacy an issue for some^C

2. ease of use/burden

2. difficulty in use/burden

easy^A

a burden^C

not time consuming^A

too busy at work for emails^C

not a burden/not a lot required/little effort to be involved^B

need to check emails regularly^C

no post or phone calls to worry about^C

takes time^C

frequently check emails/on Internet^C

go away with no access can't participate^C

user friendly^C

time on computer^C

typing is easier than writing^C

fun/ enjoyed participating^C

can receive the results^C

3. Security, privacy and confidentiality

3. Security, privacy and confidentiality

anonymity^B

online security^C

non-invasive^C

invasive (over everyday workload) ^C

lack of pressure^C

genuine study or hoax^C

can participate without others knowing^C

4. participant perceived benefits to the researchers

4. participant perceived disadvantages to the researcher

decreased cost^B

easy for participants to drop out^C

greater geographic reach^B

participants can register twice^C

quick results^C

unaware who is participating^C

more likely to continue for longer f/u^C

limited research area^C

faster data entry^C

less controlled^C

quick fixes of issues while study is underway ^C

difficult for qualitative data^C

researchers compile data accurately^C

self selected participants^C

fewer dropouts^C

research may not be seen as significant as other forms^C

blind person can participate^C

those without computer/Internet access not able to participate^C

quantitative^C

continuous analysis^C

more potential participants/large number of participants^C

many advantages for researchers^C

5. technical aspects

5. technical aspects

reminders^B

forget to complete/need reminders^B

could stop when busy and return to complete it later^C

personal Internet issues/connections/need access to a computer^C

can use multimedia to assist ^C

emails may be filtered as junk/spam^C

unable to skip questions (may assist with data quality) ^C

could result in too many email requests for more^C

difficult to make changes if mistake made^C

online distractions while participating^C

6. positive effect on information quality

6. negative effect on information quality

time to think^C

honesty may be compromised^B

more honest results^C

accuracy may be compromised^B

not influenced by the interviewer^C

subjective measures^B

data collection is consistent^C

little thought if rushed^C

more accurate results^C

sensitive info not disclosed^C

was relaxed when answering questions/no stress^C

need to recall answers^C

easily correct mistakes^C

not as serious as other forms^C

no answers received^C

lower data quality^C

not judged^C

results not as valid as other forms^C

better compliance^C

self report^C

forces to answer question specifically asked^C

superficial form of research^C

aware of answers supplied/can see questions and answers^C

7. no advantages ^C

7. no disadvantages ^B

8. paper wastage ^C

9. wouldn't participate otherwise ^C