# The Causal Impact Package in R could not trace the right number in the test group

I have this sample dataset which is as follow:

2016-03-19 0.01109 0.01418
2016-03-20 0.00882 0.01445
2016-03-21 0.00953 0.00977
2016-03-22 0.01022 0.00998
2016-03-23 0.01141 0.01145
2016-03-24 0.00973 0.00966
....

As I plot the whole dataset in Excel, the trend is as following:

However, in R, when I used Causal Impact, I would get a different view for the plot data, as you can see the first panel of this plot.

Can anyone please help me with it? Why is there the difference between these two charts? The test starts from 5/19.2016. I think the impact between control group and test group should be neutral. However, in causal impact package, it's significantly positive.

• The top panel in the CausalImpact plot, by contrast, shows the observed data in the test group (black, matching the red line in the first chart) and an estimated counterfactual of the test group. The counterfactual is an estimate of what would have happened in the test group had the test group not been treated. In this particular case, since there seems to be only a single predictor variable (i.e., the control group), the expectation of the counterfactual is simply $\beta_1 \times \textrm{control group} + \beta_0$ for two model parameters $\beta_0, \beta_1$.