Question: Which polling company did better? Use all parties and both time periods (elections) in the analysis supporting your conclusions. Which parties were the most difficult to predict?

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42.4 42.8 40 40- 36.9 33.6 33.6 30.4 31 30 - election 2015 20 - 2017 10 - 7.9 7.4 7.3 7.9 0 - ob.res_con ob.res_lab ob.res_libdem pr.res_con pr.res_lab pr.res_libdem observed and predictedpolls data frame Variable name Description poll ID for each poll house Polling firm conducting the poll poll_date Date of data collection sample Sample size vote_lab Support for Labour (in %) vote_con Support for Conservatives (in %) vote_libdem Support for Liberal Democrats (in %) results data frame Variable name Description election which election (2015 or 2017) res_lab Labour (in %), result res_con Conservatives (in %), result res_libdem Liberal Democrats (in %), result