started methodology

thesis/sections/background.tex

@@ -41,11 +41,24 @@ throughout the menstrual cycle.
 
 \begin{figure}
     \centering
-    \includegraphics[width=0.7\textwidth]{background_menstrual_cycle_physiology}
+    \includegraphics[width=0.6\textwidth]{background_menstrual_cycle_physiology}
     \caption{Physiological changes during the menstrual cycle\cite{pedroso_menstrual_2022}.}
     \label{fig:background_menstrual_cycle_physiology}
 \end{figure}
 
+Not every cycle results in ovulation—a phenomenon known as anovulation—which leads to a monophasic temperature pattern.
+Anovulation can have various causes, including hormonal imbalances, stress, or underlying health conditions\cite{rosenfield_adolescent_2013}.
+
+Anovulation is reflected in temperature data as either an absence of a clear temperature rise or a rise
+that is insufficient in magnitude or duration to be considered a reliable indicator of ovulation.
+Distinguishing between ovulatory and anovulatory cycles is challenging, as the only definitive confirmation of
+successful ovulation in a clinical sense is a positive pregnancy test.
+Even ultrasound imaging can only confirm that an egg was released from its follicle—not whether it was fertilized or successfully implanted.
+
+%TODO: find source for this
+
+%TODO: show plot of different cycle types
+
 \subsubsection{Fertility Prediction}\label{subsec:fertility_prediction}
 Throughout the menstrual cycle, the chance of fertilization varies significantly.
 An egg cell released from the ovary during ovulation, can be fertilized for up to 24 hours.
@@ -56,7 +69,7 @@ as illustrated in Figure~\ref{fig:background_pregnancy_chance}.
 
 \begin{figure}
     \centering
-    \includegraphics[width=0.8\textwidth]{background_pregnancy_chance_over_time}
+    \includegraphics[width=0.7\textwidth]{background_pregnancy_chance_over_time}
     \caption{Chance of fertilization depending on the day of the menstrual cycle.
     The highest chance is around one day before ovulation\cite{dunson_day-specific_1999}.}
     \label{fig:background_pregnancy_chance}
@@ -93,4 +106,5 @@ There are usually two main goals:
 understanding the underlying mechanisms that lead to the observed data and predicting future data points based on the
 historical information and potentially external factors\cite{cryer_time_2008}
 \\
-Time series analysis encompasses various methods, ranging from simple statistical models to complex deep learning architectures.
+Time series analysis encompasses various methods, ranging from simple statistical models to complex deep learning architectures.
+Classical methods