Which form widget for (seemingly) linear input without default value?

Question

For answers in digital questionnaires, is there any reasonably well understood form widget between a horizontal group of radio buttons (or check boxes) and a slider gauge that lets the user input a seemingly linear value instead of an obviously discrete value, but doesn’t need a default that would be submitted if the user did nothing?

The best idea I could come up with, is a slider with an adjacent checkbox for “No answer” which is on by default and gets switched to off-state as soon as the slider is moved away from its default position.

Answer 1

There is already a an interface in hardware design where a potentiometer or rheostat has a switch at one of the ends of the range. In some cases, it is used as an on/off switch, e.g. for a cheap amplifier where there is a singular control (volume).

I would suggest having a similar control where sliding all the way to one side provides feedback that the control has been disabled.

ASCII art (substitute with UML):

slider  |----------------|
value   N/A      0 1 2 3 4
snap    |        | | | | |

The input starts in the N/A position, but "clicks" when the user drags the handle sufficiently far from the N/A position. If the user decides that the value is not applicable, they may simply drag it to the N/A position.

Put simply, do this:

The best idea I could come up with, is a slider with an adjacent checkbox for “No answer” which is on by default and gets switched to off-state as soon as the slider is moved away from its default position.

And indicate with a dead zone the slider skips instead of a check box.

NB: This answer assumes that the input value varies continuously rather than discretely, which is indiscernible from the former when the ratio of range to step size is large enough.

Answer 2

I will suggest you go with radio buttons over slider, because sliders lack the very important features such as: Precision, Speed, Cognitive Load etc.

Here's a fantastic study done on this topic (the article is a little long but trust me, you will enjoy the read and findings):

Exploring Slider vs. Categorical Response Formats in Web-Based Surveys

Response to the slider scale was submitted by 35 (out of 58) managers resulting in a response rate of 60%. For the radio-button scale, 39 (out of 62) managers responded resulting in a response rate of 63%. The difference between these two proportions is not statistically significant (z = 0.288, p < .78).

A second index of data quality is completion time. Respondents in the slider treatment averaged 5.93 minutes (range from 1.92 to 49.85 minutes) to complete the survey while respondents to the radio-button treatment took an average of 4.95 minutes (range from 0.15 to 2.00 minutes). The difference is not statistically significant (t = 0.593, p < .56).

http://jrp.icaap.org/index.php/jrp/article/view/509/413

Answer 3

There are ways where a neutral position can be clearly communicated to the user.

Survey Slider

A control will have a default state. It is not necessary that you take that default state into account. You can make sure the user understands that by naming appropriately.

Here is a slider with a neutral position at the center which clearly states that the default state is Not Applicable and Not Neutral. You can inform the user that having a stance is essential. Only ignore a question if it does not apply to you. I guess we need this kind of state more often so that fewer fence sitters would exist, but I digress.

Optional Sliders

Many shopping websites have price filter sliders which do not get activated until you click. Their default state is include-all. So based on your thinking, you could have a checkbox which enables the slider control and then provide a slider which has a default value.

Textbox

Reminds me of torrent applications with their bandwidth allocation forms. They have text inputs with number validations and a text to the side mentions that a value 0 means infinite or the function is not being considered. Any other numeric value is allowed. That is fairly continuous.

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Also, you can inform your users that please avoid submitting blank surveys.

Answer 4

I would suggest using push button group which acts as a radio group (only one selected at a time) but with difference that selected value can be unchecked (radio button cannot be unchecked).

In this example following values are possible:

• Left
• Middle
• Right
• None

Answer 5

Like all UI interaction widgets, they each have a specific when to use/when not to use.

Sliders are great for selecting or changing values, e.g. from 0 to 10, but they only work well when precision is not needed, e.g. it is fine if the numbers are simple integers (i.e. 1, 2, 3...) however sliders are terrible if you needed to select 17.33. (just think about a volume control - you just make it louder or quieter, but you never set the volume to a specific high precision level).

Radio buttons are for great for quickly selecting a specific thing.Even if you had 20 things, it is just one click to select what you want.

So the real difference between the Radio button and the Slider is actually the interaction cost.

The interaction cost for setting the thing with a radio button is one simple mouse click.

The interaction cost for setting the thing with a slider is much higher - click then drag. Depending on the number of things, the interaction cost goes up, e.g. you are dragging the slider through each drag step to arrive at the one you want, so if you have 10 things, and the one you want is the 10th thing, you need to visit each of the other things using a mouse drag. Mouse drag is more difficult to do than than a mouse-click, and sliding to a thing is slower than clicking the exact thing.