With a survey question in the style of “In the coming year, how will spending on cybersecurity at your law department likely change?”, it is easiest for the surveyor to make respondents choose from set of answers (we refer to them as selections devised by the firm. The selections for that question might be “Increase more than 10%”, “Increase 6-10%”, “Increase 1-5%,” and on down to “Decrease more than 10%”.
It is easier for the firm to have pre-defined selections than to give respondents free rein to type in their answer as they see fit. The analyst will endure much pre-processing to clean the inevitable mishmash of styles respondents come up with — even if the questionnaire is laden with explicit instructions. People ignore guides such as “Only enter numerals, so no percent signs or ‘percent'”; do not write ranges such as “3-5” or “4 to 6”, do not add “approx” or “~”. No matter how clear you are, respondents will often jot in whatever they want.
Page 30 of Winston & Strawn’s 2013 report on risk displays the results of a question: “Your parent company’s annual revenues/turnover for the most recent fiscal year are:” Given the plot’s six categories of revenue, the questionnaire likely laid out those categories to choose from. Imagine two rows of three selections each. The selections were likely in order from the largest revenue category to the smallest and there was probably a check box or circle to click on next to each one. See how the plot below displays the data.
With only six selections, the questionnaire can efficiently lay them all out for consideration. Instead of displaying all of the answer choices beneath the question, a drop-down question shows a text box under the question and invites respondents to click on a down arrow to review a scrollable list. They pick their (single) answer from that list and the answer is filled in for them. Drop-down questions tend to appear when there is a large list of selections, such as states of the United States or countries in Europe or months of the year. Almost all drop-downs have the capability to complete a partial entry, so that if you put in “N” Nebraska shows up and populates (fills in) the text-entry box.
Specialists in survey design recommend that drop-down questions be used sparingly. The examples above (years, months, states, countries) make sense because they have numerous choices and respondents are not evaluating which choice is best: one answer and only one answer is the right one. Demographic questions are ripe for drop-down treatment.
For most multiple choice questions, especially those with concepts and jargon, showing all choices at the same time gives respondents context as they answer the question. What you hope they are doing is considering the selections as a group and evaluating which one (or more) they favor in comparison to the others.
Winston & Strawn might have elected to use a drop-down list for the corporate revenue question. That list could have had many more revenue categories than six, which would have collected revenue more precisely, yet enforced a consistent style for the answers. On the other hand, that arrangement would have pushed respondents to think about their company’s revenue, or even to research it, and it would have taken more time for them then to spot the corresponding category from the drop-down list. Finer categories may also conflict with some respondents desire to remain anonymous or not to disclose sensitive information. Someone working at a privately-held company might be willing to click on the broad “1-5 billion” choice but not want to disclose a more specific revenue number.