Introduction
I recently began investing and was wondering how good analysts are at predicting the future of a company. So here is a short data analysis of my curiosity!
In short, we will be answering these hypotheses:
 Price targets can accurately reflect the future price of a company.
 Some analysts can predict better than others.
 A “buy” or “outperform” rating will on average predict a stock moving up.
 Some analyst ratings are better than others.
 If we were to invest only in stocks with “buy”/”outperform” ratings, we can beat the market.
A price target is the price a financial analyst believes that a stock will reach in a year.
A performance rating is the rating a financial analyst assigns a stock that comes from their combined research and analysis of the company.
Methodology
Since my investments are mostly in Canada, I will be focusing on Canadian equities. To reduce the amount of noise, I looked at companies with the following conditions:
 Listed on the TSX
 Market cap over $1 billion
 Stock price over $5
The source data for companies can be found here: http://www.theupside.ca/listtsxstocksmarketcapitalization/ .
All source code can be found here: http://github.com/ayoungprogrammer/pricetargets
Next, to get the price targets and performance ratings, I used Marketbeat and for stock price information, I used the “unofficial” Yahoo Finance api . One restriction is that Marketbeat only had ratings for the last 2 years but it should be enough data to look back at enough ratings.
For each analyst rating assignment, I looked at the 10 day average centered around when it was assigned and the 10 days average centered around a year in time.
After some webscraping and html/json parsing we have the dataframe with sample rows:
ticker  analyst  target  rating  aver_close_at_analysis  analysis_date  aver_close_at_12m  12m_date  

0  RY  TD Securities  78.00  Hold  70.282856  20160302  97.832857  20170302 
1  RY  Scotiabank  77.00  Outperform  70.282856  20160302  97.832857  20170302 
2  RY  TD Securities  80.00  Buy  69.029999  20160225  97.656251  20170225 
Each row corresponds to a rating issued by an analyst with the following attributes:
 ticker: Ticker symbol
 analyst: Analyst who rated
 target: Target price issued by analyst
 rating: Rating issued by analyst
 aver_close_at_analysis: 10 days average stock price centered on analysis date
 analysis_date: When the analysis was issued
 aver_close_at_12m: 10 days average stock price centered 12 months from analysis date
 12m_date: 1 year from the analysis date
Results
We can calculate the error between the target price and actual price as follows:
Let
( t = ) target price,
(p_0 = ) price at analysis,
(p_1 = ) price at 12 years after analysis
(error = 100 times frac{t – p_0}{p_0} – frac{p_1 – p_0}{p_0} )
Intuitively, this is difference in percentage change from the prediction and the actual. For example, error = 5 means the target price was 5% higher than then actual percentage change.
In code:
df['target_perc'] = (df['target']  df['aver_close_at_analysis'])/df['aver_close_at_analysis'] * 100 df['real_perc'] = (df['aver_close_at_12m']  df['aver_close_at_analysis'])/df['aver_close_at_analysis'] * 100 df['error'] = (df['target_perc']df['real_perc']) df['abs_error'] = abs(df['error'])
ticker  analyst  target  aver_close_at_12m  target_perc  real_perc  error  

0  RY  TD Securities  78.00  97.832857  10.980122  39.198750  28.218627 
1  RY  Scotiabank  77.00  97.832857  9.557300  39.198750  29.641449 
2  RY  TD Securities  80.00  97.656251  15.891643  41.469292  25.577649 
A quick glance at the data shows that some of the ratings have very high variance. Therefore, we should try to reduce the noise of our error measurement by getting rid of some outliers. We will do so by removing outliers in the 10th and 90th percentiles. We also remove analysts with less than 100 ratings, so we can compare the most important analysts.
With pandas, we can easily group the data by analyst and aggregate attributes with different functions:
def filter_tail(data, p1=10, p2=90): q1 = np.percentile(data, p1) q3 = np.percentile(data, p2) return data[(data > q1) & (data 100].sort_values(by='mean_no_outliers')
analyst  std  mean  mean_abs_err  10p  90p  count  

48  National Bank Financial  16.365463  2.532164  13.425469  40.092491  30.074729  251 
3  BMO Capital Markets  18.982738  2.282366  14.435614  55.866637  35.678834  248 
7  Barclays PLC  16.120963  0.586090  13.128664  35.657920  37.853971  212 
20  Desjardins  18.972093  0.542214  15.355082  49.563907  33.312509  115 
12  Canaccord Genuity  18.101054  4.703447  14.967193  35.795798  47.363220  302 
10  CIBC  19.098723  4.960119  15.799013  31.113204  48.409297  446 
58  Royal Bank of Canada  18.198846  5.544864  15.402881  34.362247  50.268754  584 
66  TD Securities  20.179027  5.868849  17.002451  44.254427  47.655748  551 
54  Raymond James Financial, Inc.  21.500147  7.580748  18.711069  42.025280  51.284896  269 
62  Scotiabank  18.735960  7.741048  15.962621  32.351408  53.038985  706 
We can also plot the means and standard deviations as error plots:
From the aggregate table, we see that Barclays PLC has the least mean absolute error, i.e., its error is closest to 0 and is the most accurate. Barclays PLC also has the “tightest” standard deviation, so it is also the most precise. However, we see that the standard deviations for each analyst is very large; so the precision of each analyst is very low. Barclays PLC has a standard deviation of 16% which we can interpret as 95% of price targets will be +/ 32% off. For example, if TD Bank current stock price is $100 and Barclays PLC gives a price target for $100, all we can reasonably expect is the stock price to range from ~$70 to ~$130.
Thus we can answer our first two hypotheses:
 Analysts are on average, accurate in their predictions with their mean error close to 0. However, price targets cannot precisely predict the future of a company in 12 months.
 According to the data, Barclays PLC has the most accurate and precise price targets, but only by a small margin.
A more intuitive image of precision vs accuracy:
Next, we will look at analyst ratings and explore their relation to stock performance.
Using pandas again, we can easily filter out price targets with no rating and only take the ratings from analysts that care about (in the previous table). We can also easily group by each analyst and rating and aggregate with different functions on different attribute.
ratings = df[(df['rating'] != 'NaN') & (df['analyst'].isin(analysts['analyst']))] ratings_agg = ratings.groupby(['analyst', 'rating'], as_index=False).agg({ 'error': { 'mae': lambda xs: np.mean(np.abs(filter_tail(xs))), }, 'real_perc': { 'mean': 'mean', 'median': 'median', '10p': lambda xs: np.percentile(xs, 10), '90p': lambda xs: np.percentile(xs, 90), 'count': 'count', }, 'target_perc': { 'median': 'median', '10p': lambda xs: np.percentile(xs, 10), '90p': lambda xs: np.percentile(xs, 90), } }) ratings_agg.columns = list(map('_'.join, ratings_agg.columns.values)) ratings_agg[ratings_agg['real_perc_count'] > 10]
Attributes:
 target_perc_10p: 10th percentile for price target change percentage
 target_perc_90p: 90th percentile for price target change percentage
 tarc_perc_median: median for perice target change percentage
 error_mae: mean absolute error
 real_perc_10p: 10th percentile for real price change percentage
 real_perc_90p: 90th percentile for real price change percentage
 real_perc_median: median for real price change percentage
 real_perc_count: number of ratings
 real_perc_mean: mean of real price change percentage
Sample rows:
analyst_  rating_  target_perc_10p  target_perc_90p  target_perc_median  error_mae  real_perc_10p  real_perc_count  real_perc_mean  real_perc_90p  real_perc_median  

0  BMO Capital Markets  Market Perform  0.249542  23.049416  7.826429  17.048387  13.624028  82  29.306269  86.571109  11.962594 
2  BMO Capital Markets  Outperform  9.333289  34.091310  18.863216  13.267287  13.430220  116  22.215401  64.711223  15.109094 
5  Barclays PLC  Equal Weight  5.964636  10.834989  4.672844  11.317883  23.540832  72  11.511754  37.461244  9.239600 
Now we take only analyst ratings with at least 20 and then sort by stock performance (change in stock price over a year). We can take the top 10 and perform more analysis on those.
top_ratings = ratings_agg[ratings_agg['real_perc_count'] > 20] top_ratings = top_ratings.sort_values('real_perc_mean', ascending=False) top_ratings['analyst_rating'] = top_ratings['analyst_'] + ' ' + top_ratings['rating_'] top_analyst_ratings = top_ratings['analyst_rating'].head(10) top_analyst_ratings
Sorted by real price change percentage:
analyst_  rating_  target_perc_10p  target_perc_90p  target_perc_median  error_mae  real_perc_10p  real_perc_count  real_perc_mean  real_perc_90p  real_perc_median  analyst_rating  

32  National Bank Financial  Sector Perform  0.277827  45.337101  8.695651  14.170428  5.738096  81  29.887596  61.182293  17.410111  National Bank Financial Sector Perform 
0  BMO Capital Markets  Market Perform  0.249542  23.049416  7.826429  17.048387  13.624028  82  29.306269  86.571109  11.962594  BMO Capital Markets Market Perform 
54  TD Securities  Action List Buy  18.333724  77.701954  38.001830  19.629657  0.893705  36  28.334038  71.459495  15.928740  TD Securities Action List Buy 
21  Canaccord Genuity  Buy  8.340735  61.226203  24.085974  18.796959  16.561733  177  27.086690  86.234464  18.039215  Canaccord Genuity Buy 
31  National Bank Financial  Outperform  7.705539  53.579343  18.929633  12.407454  1.526925  115  24.524428  59.093628  22.213398  National Bank Financial Outperform 
2  BMO Capital Markets  Outperform  9.333289  34.091310  18.863216  13.267287  13.430220  116  22.215401  64.711223  15.109094  BMO Capital Markets Outperform 
14  CIBC  Sector Outperformer  9.714648  59.846481  33.652243  21.688542  14.518562  44  22.205022  60.020932  22.218981  CIBC Sector Outperformer 
43  Royal Bank of Canada  Sector Perform  0.678788  36.516168  11.101983  13.099112  11.590060  220  21.330160  51.282201  10.498096  Royal Bank of Canada Sector Perform 
36  Raymond James Financial, Inc.  Outperform  9.437804  54.483693  21.236522  15.914385  18.695776  106  20.773835  59.159844  13.004491  Raymond James Financial, Inc. Outperform 
49  Scotiabank  Outperform  7.239955  50.402485  19.082141  15.926344  21.632875  246  18.407885  51.023159  14.897374  Scotiabank Outperform 
We can make an error plot for the mean and standard deviation of the real percentage change for each analyst rating:
We can see that stocks with the top analyst ratings go up on average 25% in a year which is very good. Based on the error plot, TD Security Action List Buy seems to perform the best in terms of high mean and lower variance. Although there is high variance, the mean is more meaningful in this case. If we were to invest $1000 in each of the stocks when were given the rating, we would make about $1250 on average after a year, which is what we really care about. The TSX index went up 11% and TSX index annualized return is 9.1%. So we’re actually beating the market by ~16% with this strategy!
However, keep in mind that this data is for the last 2 years and is not indicative of future performance. On the other hand, I believe this strategy could make sense since analysts put significant effort and research into their rating and also because of the influence of the rating. People probably trust the analysts and would likely invest knowing that the stock has a good rating thus self fulfilling the rating.
With this analysis, we can conclude our last 3 hypotheses:
 A buy or outperform rating will on average go up on average by 1520%.

TD Security Action List Buy appears to be the strongest indicator for a stock to perform well.

If we buy stocks with the top 10 ratings when they get issued and sell in exactly one year, we will beat the market by ~16%.
Conclusion
 Price targets aren’t a good indicator of where the price of a stock will go.
 The top performance ratings are a good indicator for a stock performing well.
 You could possibly beat the market by only buying stocks with sector outperforms or buy ratings and selling in one year.
Please keep in mind that I am by no means a financial expert and am not certified to give financial advice.
All the code can be found here: https://www.github.com/ayoungprogrammer/pricetargets