Welcome to the LimeSurvey Community Forum

Ask the community, share ideas, and connect with other LimeSurvey users!

Calculate age in an Equation type question, using Date of Birth

  • tfj
  • tfj's Avatar Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
11 years 6 months ago #84840 by tfj
Denis, benitov, tpartner:

Many thanks to each of you! My limited knowledge of javascript and upcoming deadlines make for a lethal combination! I am very thankful for this forum and your help!

tfj
The topic has been locked.
  • tpartner
  • tpartner's Avatar
  • Online
  • LimeSurvey Community Team
  • LimeSurvey Community Team
More
11 years 6 months ago #84841 by tpartner
You're welcome, I'm glad we could help.

Cheers,
Tony Partner

Solutions, code and workarounds presented in these forums are given without any warranty, implied or otherwise.
The topic has been locked.
  • tfj
  • tfj's Avatar Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
11 years 6 months ago #84933 by tfj
We have been testing this solution and have found something strange when using Internet Explorer 8. When calculating the age for a person with a Date of Birth prior to 2000, the answer for age puts a "19" in front of the actual age. For instance, if we put "June 10, 1985" for the date of birth, we get 1927" instead of "27."

In Firefox, this works perfectly.

I figure it must have something to do with a setting within Internet Explorer, and not a problem with the code. If so, we may not be able to use the solution since there are so many users in the field.

Any thoughts?

Thanks!

tfj
The topic has been locked.
  • TMSWhite
  • TMSWhite's Avatar
  • Offline
  • LimeSurvey Community Team
  • LimeSurvey Community Team
More
11 years 6 months ago #84934 by TMSWhite
Date math is such a common need that we really ought to add date-related functions to Expression Manager, such as day(), month(), year(), age(date_of_birth [, today]), etc.
The topic has been locked.
  • tpartner
  • tpartner's Avatar
  • Online
  • LimeSurvey Community Team
  • LimeSurvey Community Team
More
11 years 6 months ago #85032 by tpartner
tfj, I don't have IE8 here to test but try changing:
Code:
var age = (today_year) - birth_year;

To:
Code:
var age = Number(today_year - birth_year);

Cheers,
Tony Partner

Solutions, code and workarounds presented in these forums are given without any warranty, implied or otherwise.
The topic has been locked.
  • tpartner
  • tpartner's Avatar
  • Online
  • LimeSurvey Community Team
  • LimeSurvey Community Team
More
11 years 6 months ago #85033 by tpartner

Date math is such a common need that we really ought to add date-related functions to Expression Manager...

Great idea Tom.

Cheers,
Tony Partner

Solutions, code and workarounds presented in these forums are given without any warranty, implied or otherwise.
The topic has been locked.
  • tfj
  • tfj's Avatar Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
11 years 6 months ago #85043 by tfj
I changed the line to:

var age = Number(today_year - birth_year);

The calculation still places a "19" to the front of the age in Internet Explorer 8 (for dates of birth prior to 2000), but not in Internet Explorer 9 or Firefox 14. For example, the age may be calculated as 1929 instead of 29. For the years 2000 and later, the age is calculated correctly.

For now, in order to meet my deadline, I added the two questions (Date of birth and age) in one of our surveys, but hid the age question and commented out the code. That way, in case a script fix comes up, I can put it in without deactivating the survey. I am still calculating the age after-the-fact with a MySQL script.

Thanks, all!

tfj
The topic has been locked.
  • tfj
  • tfj's Avatar Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
11 years 6 months ago #85210 by tfj
I believe I found a solution, after much digging in PHP reference manuals, web searches, etc. I am now able to perform date calculations using the Expression Manager. I modified an example given in PHP and MySQL Web Development, Fourth Edition, by Welling and Thomson (pp. 477-478) (to give proper credit).

Here's what I did:

1) Created a Date of Birth question, of type "Date." The question code I used was "DateofBirth," which you will see in step #2 below. For our purposes, all dates are mm-dd-yyyy.

2) In a separate group that follows the Date of Birth question, I made up an Equation type question, with the following in the "Question" box:

{floor((time() - mktime(0,0,0,substr(DateofBirth,5,2),substr(DateofBirth,8,2),substr(DateofBirth,0,4)))/(365.25*24*60*60))}

This question may be hidden, depending upon your particular needs.

If you need to calculate days, then take out the "365.25" in the script, and so on.

So far in my testing, this seems to be working, but someone may find an improvement, etc. If so, I would appreciate your sharing it.

One other note: the more I use the new Expression Manager, the more I appreciate it.

tfj
The topic has been locked.
More
11 years 6 months ago #85320 by Ben_V
Very nice solution...
Maybe the improvment could be to get it working with the 2 questions in a same group :unsure:

I attach the sample survey I've created to make a try.

Thank you to share...
Ben/

Benoît

EM Variables => bit.ly/1TKQyNu | EM Roadmap => bit.ly/1UTrOB4
Last Releases => 2.6x.x goo.gl/ztWfIV | 2.06/2.6.x => bit.ly/1Qv44A1
Demo Surveys => goo.gl/HuR6Xe (already included in /docs/demosurveys)
The topic has been locked.
More
11 years 2 months ago #91050 by PawsInMotion
These have all been incredibly helpful! Thank you!

Here's a trick I'm trying to figure out though (without knowing perl or much scripting at all):

How do I show year and month (and, optionally, days) from birth as chosen in the previous question.
Some of my clients aren't a year old yet (dogs) or are a year and some months.

I appreciate the help. I'll keep noodling with this code. At least I figured out that 'floor' means to round the answer.

{floor((time() - mktime(0,0,0,substr(DateofBirth,5,2),substr(DateofBirth,8,2),substr(DateofBirth,0,4)))/(365.25*24*60*60))}
The topic has been locked.
  • tfj
  • tfj's Avatar Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
11 years 2 months ago #91155 by tfj
PawsInMotion:

The code I used is modular in the sense that you can substitute values in it to come up with whatever type of date measurement you need.

For instance, instead of using the following for years:

{floor((time() - mktime(0,0,0,substr(DateofBirth,5,2),substr(DateofBirth,8,2),substr(DateofBirth,0,4)))/(365.25*24*60*60))}

you can change it to:

{floor((time() - mktime(0,0,0,substr(DateofBirth,5,2),substr(DateofBirth,8,2),substr(DateofBirth,0,4)))/(24*60*60))}

for the number of days. From there, you could use Equation-type questions to come up with months and days, etc.

I tested this on a couple of cases and they seemed okay. Please let me know if your experience is different.

tfj
The topic has been locked.
More
10 years 8 months ago #97877 by DWS
the example works fine... but if yo hide the question then you can't use the value on following questions :(
The topic has been locked.

Lime-years ahead

Online-surveys for every purse and purpose