Skip to main content

ahhh, reliability and validity

Reliability and validity are concepts that many students (and researchers!) have a hard time keeping straight.

Validity: the extent to which an empirical measure adequately reflects the real meaning of the concept under consideration. (how closely do you come to hitting the bull's-eye (presumably the concept you actually want to measure?)

Reliability: whether a particular technique, when applied repeatedly to the same object, will yield the same results each time.

With that in mind, some pictures:

The "hits" are far from the bull's-eye (low validity);
and all over the place (low reliability). 
Hits are closer to the bull's-eye (higher validity); but
the hits are also all over (low reliability).
Hits are FAR from the bull's-eye (low validity); but they are
clustered in the same area-- the same answers are
received with each test (high reliability).
(more common with survey research (of course we strive
to hit the bull's-eye!))
Finally, 
Hits are clustered in the bull's-eye-- high validity and high reliability.

Comments

Popular posts from this blog

add a public Google calendar to your Android device

Subscribing to a Google calendar on Android is actually a two-step process. You must first subscribe to the calendar using the web version of Google Calendar and then add it to your Android device.
Subscribing to ical on Google Calendar web:
Step 1: go to Google Calendar on the web
Step 2: Choose "Other calendars"
Step 3: In the dropdown menu, choose "Add by URL"
Step 4: Insert the calendar's ical address (probably provided to you by your instructor in the syllabus), click "Add Calendar," and you should be all set.
Adding subscribed calendars to Android: Step 1: On your Android device, you may have to clear the existing calendars and re-sync the data for a new calendar to show up. Settings / Applications / Manage Applications / Calendar -> Clear Datathen Settings / Applications / Manage Applications / Calendar Storage -> Clear Data Wait a few minutes and you should be able to see the new calendar. If it does the new calendar does not show up, also …

are you better off than your parents?

Here's a link to the Bureau of Labor Statistics CPI calculator. You may also want to consider this article and the accompanying graphic: A Rough Ten Years for the Middle Class


So are you better off than your parents?