In reply to Matthias Buch-Kroman.

The FREQ variable should be an integer because it is shorthand for specifying the number of rows that this observation represents. That is the definition (or interpretation, if you prefer) of a frequency variable.

Data sets contain observed values, not probabilities. You observe, count a certain number of each color, and then analyze the results. You can ask questions like "are my data consistent with the hypothesis that red occurs 60% of the time." Many statistics depend on the sample size to determine inference and uncertainty. In your example, how many colors are observed? The number of observations is the sum of the FREQ variable, so your example is telling me that you observed 0.6 + 0.4 = 1 value. Unfortunately, you can't do statistics on one observation. And what was the color that you observed? Your example does not specify it.

Yes, you can use the WEIGHT variable to encode uncertainty, and the article describes how to interpret weights. In particular, your example would have two observations, but the "red" row would have greater influence on the parameter estimates than the "green" row. But I suspect that this is not what you are trying to acheive.