Physics89L

Notes and materials for Week 5

Topics covered: Covariance, correlation, and chi-square fitting.

Scientific context and resources

In the second Jupyter notebook we will be using the output of some data analysis done using data from the Fermi Gamma-ray space Telescope. It is the same data we used last week; except this time we will be looking for a long-term trend in the Vela pulsar, to see if it is slowly getting brighter or fainter.

Python functions reference

We will not be using a lot of new python functions this week. Here are the important ones that we will be using.

Function Name What it does
plt.figure Make a matplotlib figure, useful for making figures with subplots
fig.subplots Makes subplots for a figure
np.cov Compute the covariance matrix between multiple data series
np.corrcoef Compute the correlation coefficient between multiple data series
plt.contour Make a contour plot, ie., show the contours correspond to a series of values
scipy.stats.minimize Find the parameter values that minimize a user-provided “cost function”
scipy.stats.chi2 Interact with a $\chi^2$ distribution, e.g., to compute a p-value