Table:
|  |  | Three Months Ended |  | % Variation |  |
| --- | --- | --- | --- | --- | --- |
|  | December 31, 2019 | September 29, 2019 | December 31, 2018 | Sequential | Year-Over-Year |
|  |  |  | (Unaudited, in millions) |  |  |
| Automotive and Discrete Group (ADG) | $924 | $894 | $967 | 3.3% | (4.5)% |
| Analog, MEMS and Sensors Group (AMS) | 1,085 | 968 | 988 | 12.1 | 9.9 |
| Microcontrollers and Digital ICs Group (MDG) | 742 | 688 | 689 | 7.9 | 7.6 |
| Others | 3 | 3 | 4 | — | — |
| Total consolidated net revenues | $2,754 | $2,553 | $2,648 | 7.9% | 4.0% |
Paragraphs:
On a sequential basis, ADG revenues were up 3.3%, driven by an increase in volumes of approximately 8%, partially offset by a decrease in average selling prices of approximately 5%, mostly attributable to product mix.
AMS revenues increased 12.1% driven by Analog and Imaging products. AMS increase was due to an increase of approximately 5% in average selling prices, entirely due to product mix, and to higher volumes of approximately of 7%.
MDG revenues increased by 7.9%, mainly driven by Microcontrollers, due to both higher average selling prices of approximately 6%, entirely due to product mix, and higher volumes of approximately 2%.
On a year-over-year basis, fourth quarter net revenues increased by 4.0%. ADG revenues decreased 4.5% compared to the year-ago quarter on lower revenues in both Automotive and Power Discrete. The decrease was entirely due to lower average selling prices of approximately 4%, while volumes remained substantially flat. The decrease in average selling prices was a combination of less favorable product mix and lower selling prices.
AMS fourth quarter revenues grew 9.9% year-over-year, mainly driven by Analog and Imaging. The increase was entirely due to higher average selling prices of approximately 18%, entirely attributable to product mix,
partially offset by lower volumes of approximately 8%. MDG fourth quarter revenues increased by 7.6%, mainly driven by Microcontrollers. The increase was due to higher average selling prices of approximately 9%,
entirely due to improved product mix.
Question:
What led to increase in the revenue of ADG on sequential basis?
Answer: driven by an increase in volumes of approximately 8%, partially offset by a decrease in average selling prices of approximately 5%, mostly attributable to product mix.