1st create points using Latitude and longitude data (X &Y), 

2nd step overlay your point data on DME model and extract data and save as Z 

If you have a good enough resolution digital elevation model (DEM) you should be able to get that data following the steps from the previous answer (Prakash Mesta). However it depends on how accurate you need your elevation data, whats available and how your going to analyse the data.

Hope this helps, good luck.

Thanks for taking the time to answer. Unfortunately I don't think I explained what I need very well. What I was wondering is: where can I find data on altitude? Is there a look-up table that contains latitude, longitude and altitude that is freely available online?

Is the DME (?abbreviation) model something that I can download? I have googled but not come up with anything...

It all depends om what area(-s) you are studying. Digital Elevation Models are often supplied by state authorities, but are not always public ally available. Most nationwide DEMs have a resolution of 10x10 or 20x20 metres (or similar), but some also have higher resolution LiDAR based DEMs available for free download (Finland is one example). Finding out where and how to get the data for the area you want to study should therefore be a priority. Universities can have the data available, but that depends.

Hope this is of some help to you!

Hi Oyebode,

If you send me  Latitude and longitude I can try using my software and send it back to you.

Gabriel

Dear Oyinlola,

There is several possibilities. For examples: SRTM (Shuttle Radar Topography Mission) data (3 arc sec ~ 90 m resolution or better depending on the area) at http://srtm.csi.cgiar.org/SELECTION/inputCoord.asp or Aster GDEM at http://gdem.ersdac.jspacesystems.or.jp/. Maybe you are looking for such type of data.

Hope this helps,

With best wishes,

Rasto

Dear Oyinlola,  you can use ASTER- DAM data which is freely available on http://gdem.ersdac.jspacesystems.or.jp/  or https://lpdaac.usgs.gov/data_access for elevation information. and And X,Y data layer overlay on DAM data with the help of Arc GIS Software

1.-Open Google Earth

2.- Add a new target ( put x and y data),

3,. Elevation appears in the bottom bar google earth

Just to clarify, most of the answers you got require that you have and know how to use ArcGIS. that way you can use DEM data and put it together with your data base... but as I mentioned you need to have and use ArcGIS. 

Octavio, how precise would google earth be?

good luck!

If you are using Arc products, google GeoTopo for a DEM (Digital Elevation Model) of the world. Zoom to your basic area of interest, create a mask, and cut out your piece of the map.

You could use this  https://developers.google.com/maps/documentation/elevation/

example here: http://stackoverflow.com/questions/21593868/extracting-elevation-from-website-for-lat-lon-points-in-australia-using-r

Thank you all. These answers are all very helpful and I can see that although there isn't a downloadable table that I can easily use as a look-up, there are other ways to get the information.

My data is currently in STATA format as that is what I will use for my analyses. I have about 41,000 records and many variables (so methods involving inputting numbers one at a time won't be adequate for my purposes). What I was originally asking for is an open access look-up table, so I could simply write a do. file to look up altitude based on the recorded latitude and longitude for each record, but it seems one doesn't exist.

I wanted to then examine the association between altitude of the participants place of residence and various health outcomes.

You can download altimetry 30x30 meters (ASTER GDEM data) based on satellite observation, at the link: http://www.jspacesystems.or.jp/ersdac/GDEM/E/4.html