Weighted vs. Unweighted


Nielsen Media Research included sample weights in their PxP data starting in September 2003. Prior to that date, the sample was "self-weighted", meaning that the sample represented the population for all demographic characteristics. In September, Nielsen began merging Local People Meter (LPM) sample households into the national sample. There are proportionally more LPM households in the LPM markets than there are national households in the national sample, thus requiring the introduction of weights to balance the sample.

What is the difference between the Weighted and Unweighted Nielsen Sample?
When should I use the Weighted sample?
As a rule of thumb, use the Weighted sample.  Weighted sample analysis, which is the default, is more accurate in representing the population, and should generally be used.
When should I use the Unweighted sample?
Unweighted sample analysis could be used if:
How do I know which sample I am using?
A Weighted (Wgt) and Unweighted (UnWgt) indicator appears in the demographic description line to indicate whether analyses uses the Nielsen Weighted or Unweighted sample.
FOR EXAMPLE, below is the demographic description line for a Weighted (left) and Unweighted (right) sample:

To Toggle between the Weighted and Unweighted sample