Mark:

this is a previous post i sent out in 2007 to Tanya - as for the NP score itself, i'm not a big fan -- your question is referenced toward the end

Tanya:

don't know if there is an answer to your question but when you calculate the net promoter (NP) score, the z-test is not applicable. The reason for this is that when when you track this measure you may be double-counting a change in the proportion of respondents. This is because when the proportion who answered 9 or 10 goes up by 1 pct point you will be doubling that increase if the proportion who answered 1 to 6 decreased by 1 pct point.

The resulting NP score is actually not a proportion -- it's just a calculated score. You would expect much greater variation with a NP score than a top 2-box percentage.

on a separate note, an easy way to track net promoter scores in spss is to recode 9-10 to +100, 7-8 to 0, and 1-6 (or 0-6) to -100 -- then just compare the mean of the new variable over over time.

you might want to check with the company that advocates this technique http://www.satmetrix.com/netpromoter/index.htm to see what they say about statistical differences over time

On Fri, Mar 12, 2010 at 6:04 AM, Mark Webb <targetlinkmark@gmail.com> wrote: > Some market researchers compute a score called Net Promoter Score. > > I'm trying to write syntax for this score but am struggling. > Has anyone does this? - any assistance will be appreciated. > > NPS is computed from an 11 point scale [0-10] of recommendation where 10 > = Extremely Likely to Recommend. > > The 11 point scale is reduced to 3 points > 0-6 = Detractors > 7-8 = Passives > 9-10 = Promoters > > The NPS = %Promoters - %Detractors > > An example - > > Detractors 10% > Passives 30% > Promoters 60% > > NPS = 60-10=40 > > The only data I have is a rating from each respondent on the 0-10 > scale-one variable. > I'm struggling to compute the percentages into new variables so that I > can subtract them. > > As the percentages will vary if a filter is applied it will be necessary > to recalculate for each new filter. > Regards > > -- > Mark Webb > > Line +27 (21) 786 4379 > Cell +27 (72) 199 1000 > Fax to email +27 (86) 5513075 > Skype webbmark > Email targetlinkmark@gmail.com > > ===================== > To manage your subscription to SPSSX-L, send a message to > LISTSERV@LISTSERV.UGA.EDU (not to SPSSX-L), with no body text except the > command. To leave the list, send the command > SIGNOFF SPSSX-L > For a list of commands to manage subscriptions, send the command > INFO REFCARD >

===================== To manage your subscription to SPSSX-L, send a message to LISTSERV@LISTSERV.UGA.EDU (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD