One day impressions drop... how to figure out why?

[CalicoKitty2000]

I went back and looked through webmaster tools.  I had around 3000 impressions per day leading up to 3/10/2014. Then on 3/11/2014, I dropped to 1000 impressions per day.  Is there a good way to figure out what happened? Anyone know if there was a google update that day.

[DJ123]

Did your traffic also drop at the same time, by a similar percentage?

[RobertFisher]

Calico

Are you saying your total impressions per day are 3K and then in a single day it dropped to 1K and never increased again? Remember, it is very hard to look at one metric in a vacuum and draw any conclusion; I would say this is especially true when it is impressions in WMT. DJ123 asked about traffic which is a very good question. Another thing I will suggest since I know you are making changes regularly to the site is always annotate the changes in analytics so that you have benchmarks to check changes against. 
Give us as much additional data as is possible and we will try to assist.

Best

Robert

[CalicoKitty2000]

I've been hands-off for since February because my dad has been really sick.  So, no major changes.

What I am seeing is this:

1. In Google Webmaster Tools, the impressions were 3000 per day and dropped to 1000 per day to never return. The clicks averaged around 70 per day then dropped to average around 50 per day. I looked at the keyword lists and did not see anything significant change accept for overall lower volume.

2. I looked in Google Analytics and it shows around 1000 impressions per day before 3/11 and 500 per day afterwards.  I DO NOT see any drop in clicks AT ALL.  The total number of clicks is WAY higher each day than in Google WMT since I do a PPC campaign.  So, if I choose organic only, I still see no change.  It is also different numbers day by day than WMT.

So, I guess my question now is... which one do I trust?

[DJ123]

So what you're really saying is that your click percentage is double what it was before...

I would only take the impression count with a grain of salt.  Also, take a look at all your analytics sources and look at ratios rather than just the raw #s; you will be able to get some more actionable data from ratio analysis.  Also, personally, and again this is a preference and some may like it or hate it, but I like statcounter.com for some analytics.  I have also used Kissmetrics which depending on what your business model is, can also be good (also shout out to CrazyEgg).  Worry much more about how many unique visitors are going to the site and your conversion rate (for whatever product it is).

If you focus on efficiency, you won't have to put as much input (unique visitors) in the top of the funnel.  Of course, this is easy for me to say because I have no practical advice on how to make your machine more efficient, but just that it is a good thing to focus on.

[MoosaHemani]

I believe Google webmaster and GA are both trusted tools but if I have to choose one of them I will go with analytics tool as its real time where as webmaster tools take time to get updated. If you lost impression as well as traffic from search in a day you probably have to check your rankings and see if you lost rankings as well in-case of you probably knows the action plan.

Also check the drop date and compare it with the Google penalty calendar to see if you are a suspect of Panda or Penguin.

Hope this helps!