Update for 7 Feb. Total number of cases:
"Cases" are number of cases reported in mainland China (M. China) and rest of the world (ROW), from John Hopkins University.
Y-axis is plotted as a logarithm, so straight lines on graph show the exponential rate.
Coloured lines on chart are lines of best fit to mainland China data showing the daily increase in number of cases.
The rate of increase each day:
"Daily change" for mainland China (M. China) and rest of the world (ROW), from John Hopkins University.
Coloured lines on chart are linear lines of best fit.
Lines extending beyond data points are extrapolated and therefore not data-based but are speculative.
The rate of increase each day is trending downwards which is good. In the last few days the rest of the world (ROW) trend has gone upwards due to newly discovered cases eg on cruise ships. As the ROW has much lower overall numbers the data for ROW tends to bounce around a bit, so this might be factor rather than any long-term change. The linear trend is still strongly downwards.
Overall the trend for mainland China matches the trend for the ROW pretty closely, with the total numbers in the ROW being about 1% of the mainland China numbers. If there is under reporting in either series it is either (1) too small to notice or (2) both series under-report by the same proportional amount.
The reduction in daily increase is significant. For example, had the initial trend of 50% per day increase continued to today, there would be about 320,000 cases in China and about 3,200 cases in the ROW, whereas the actual numbers today are about a tenth of that. So major strides have been made to contain the spread of nCoV so far.