Fix typos kriging

kriging/kriging.tex

@@ -418,15 +418,15 @@ \section{Ordinary kriging}%
 \section{Other types of kriging}
 
 \begin{description}
-\item[Directional kriging] is useful when the similarity of points differs according to different directions, \eg\ north-south vs.\ east-west.
+\item[Directional kriging] is useful when the similarity of points differs according to different directions, \eg\ north-south versus east-west.
 It involves creating variograms for different directions.
 \item[Block kriging] attempts to obtain a local trend for an area around a point (rather than just at a point).
 It can be used to obtain smoother results.
 \item[Cokriging] applies kriging to multiple correlated variables.
 It is particularly useful when you want to interpolate one variable with limited sample points but there are more sample points for another correlated variable.
 \item[Indicator kriging] applies thresholds to obtain discrete values, such as presence/absence of a variable or a set of distinct classification classes.
-\item[Poisson kriging] applies kriging to data involving cummulative counts or rates.
-It is oten applied together with polygonal datasets.
+\item[Poisson kriging] applies kriging to data involving cumulative counts or rates.
+It is often applied together with polygonal datasets.
 \item[Universal kriging] fits the trend using a predefined deterministic function.
 It is tricky to use in practice because it imposes conditions on the underlying variogram.
 \end{description}
@@ -470,7 +470,7 @@ \section{Notes and comments}
 
 A relatively simple explanation of kriging with agricultural examples is given by \citet{Oliver15}.
 A standard reference textbook that is good but not so easy to follow is \citet{Wackernagel03}.
-The math covered in this chapter is partly based on the latter.
+The mathematics covered in this chapter is partly based on the latter.
 
 Two other good Youtube videos that explain kriging:
 \begin{itemize}