A weakness of the top-down approach?

- The way the typology was developed. -The FBI came up with the categories disorganised and organised after an interview with 36 sexually motivated serial killers. These serial killers behaviour are quite extreme and rare as well as the sample size being small meaning that it is an unrepresentative sample. -The serial killers could have acted under a social-desirability bias and lie to make them more likelable as they were psychopaths, making it hard to generlise to 'normal' criminals -Lacks internal validity due to the data collection from a small smaple, lowering external validity as well.