impression & clicks fall down even though the average keyword rankings have improved

I compared the performance of my website to check the impression and clicks data for the corresponding days of the current month with the previous month. I noticed that the overall impressions, and clicks of my site have fallen down as compared to the previous months, even though the average ranking position of my keywords has improved from 25 to 19. Organic traffic though remains almost the same for corresponding dates.
Anyone, please help me find out the precise reason behind this.

See original post by rahul_kp5