Otago-Southland was the stand out result in the latest BNZ-Business NZ performance in services index survey, but the good news came with a warning that it was not seasonally-adjusted.
That means the published PSI figures were subject to the swings of seasonal changes in economic activity.
Otago-Southland recorded 53.8 on the index, up from 47.6 in November and 37.7 in October. Canterbury-Westland was 54.6 but slipped from 55.3 in November.
The New Zealand index reading was 48, slightly up on November.
BNZ economist Mark Walton said the period either side of Christmas was the most obvious example of seasonal influences.
Economic activity peaked as manufacturers and retailers prepared for the Christmas rush.
There was a sharp slowdown in January as much of the country went on holiday. The seasonal peaks and troughs of the agricultural production cycle was another example.
Seasonal adjustment was a statistical technique used to remove seasonal influences and strip back the headline figures to get to the "real" story, he said.
"But this process requires that the time series is sufficiently long - at least three years, usually - so that seasonal patterns can be correctly identified."
The PSI survey, only running since April 2007, had not been running long enough.
One approach to interpreting the data was to compare the figures with those of the same month in the previous year, which avoided any problems of seasonality, Mr Walton said.
Otago-Southland recorded a reading of 44.7 in December 2007.
The New Zealand index reading of 48 was down on December 2007's reading of 53.9, suggesting a slowdown much more in keeping with the recessionary backdrop in place.
The generally gloomy economic backdrop was still of major concern to many service sector operators judging by the comments received for respondents to the December survey.
December's improvement was welcome but the underlying story was still much weaker than the headline suggested, he said.
Business NZ chief executive Phil O'Reilly said that although the result was a slight improvement, the New Zealand result remained in a consistent band of contraction.
That would most likely continue through 2009.
Last year ended with nine of the 12 months in contraction and it was a year that most businesses would like to forget, he said.
