LaTeX Forum

    node distance=1.5cm and 2.5cm,

\node (research) {Research design};
\node (traditional) [below left=of research] {Traditional class};

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc, positioning, decorations.pathreplacing}
\newlength\braceoffset
\setlength\braceoffset{2.5mm}
\newif\ifshowinfo
\showinfotrue
\begin{document}

\begin{tikzpicture}[>=stealth,
    node distance=1cm and 5mm,  %1.5cm and 2.5cm,
    every node/.style={draw, rectangle, text width=3cm, align=center, rounded corners, minimum height=1cm},
    week/.style={thin, midway, text width=2cm},
    wide/.style={minimum width=7cm, text width=5cm},
    class/.style={fill=blue!20},
    my brace/.style={semithick, decorate, decoration={brace, amplitude=3mm}},
    my line/.style={black!50, thick},
    info/.style={minimum height=1ex, text width={}, draw=none, blue!75!black},
    pre/.style={my line, ->},
    rev/.style={my line, <-}
]

\node (research) [text width=4cm] {Research design};
\coordinate [below=2cm of research] (hrd); %Stützpunkt
\coordinate [below=7.5mm of research] (hrdl); %Stützpunkt für Linien
\node (traditional) [left=of hrd, class] {Traditional class};
\node (flipped) [right=of hrd, class] {Flipped class};
\node (pretest) [below=3.5cm of hrd, wide] {Pre-test algebra proficiency\\ Pre-test self-efficacy};
%\coordinate [below=1.5cm of pretest] (hpt); %Stützpunkt
\node (training) [below=of flipped] {\footnotesize Training sessions on the flipped approach};
\node (flipped_lessons) [below right=of pretest.south, class] {Flipped lessons};

% Arrows
\draw[my line] (research) -- (hrdl);
\draw[pre, rounded corners=3mm] (hrdl) -| (traditional);
\draw[pre, rounded corners=3mm] (hrdl) -| (flipped);
\draw[pre] (traditional)
  -- ($(pretest.north west)!(traditional)!(pretest.north)$);
% siehe `texdoc pgfmanual', Abschnitt ``The Syntax of Projection Modifiers''
\draw[pre] (flipped) -- (training);
\draw[pre] (training)
  -- ($(pretest.north)!(training)!(pretest.north east)$);
\draw[rev] (flipped_lessons)
  -- ($(pretest.south)!(flipped_lessons)!(pretest.south east)$);
% Braces + Annotations:
\coordinate[above=\braceoffset of training.north east, xshift=\braceoffset] (bbrc);
\coordinate[below=\braceoffset of pretest.south east] (ebrca);
\coordinate[right=1.5cm of ebrca] (ebrcb);
\draw[my brace] (bbrc) -- ($(ebrca)!(bbrc)!(ebrcb)$)
  node[week, right=5mm]{Weeks 1 + 2};% und mittig zur Klammer den Text nach rechts
% nur zur Demo:
\ifshowinfo
  \draw[blue!30, ->] (training.north east) |- (bbrc) node[info, near start, left]{$\delta$ (above)}
    node[info, near end, above]{$\delta$ (xshift)};
  \draw[blue!30, ->] (pretest.south east) -- (ebrca)
    node[info, midway, left]{$\delta$ (below)};
  \foreach \i in {hrd,hrdl,bbrc,ebrca,ebrcb}{%
    \draw[red!50] (\i) circle[radius=0.25mm];
    \draw[red!20] (\i) -- +(330:1) node[info, below, red!75!black]{(\i)};
  }
  \draw[red!20] ($(pretest.north west)!(traditional)!(pretest.north)$) -- +(310:5)
  node[info, below, red!75!black]{(\$(pretest.north west)!(traditional)!(pretest.north)\$)};
  \draw[blue!30, dashed]  (ebrca) -- (ebrcb) node[info, right]{gedachte Linie};
  \draw[blue!30, <->] (pretest.south) -- +(0,-1) node[info, midway, left]{node distance};
  \draw[blue!30, <->] (flipped_lessons.north west) -- +(-0.5,0) node[info, midway, below]{node distance (and)};
\fi
\end{tikzpicture}
\end{document}

 \documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning, calc, arrows.meta} % Required TikZ libraries

\begin{document}

\begin{tikzpicture}[
    node distance=1.5cm and 2.5cm,
    every node/.style={draw, rectangle, align=center, rounded corners, fill=blue!20, text width=3cm, minimum height=1.5cm},
    pre/.style={->,>=stealth, thick, draw=black!50},
    post/.style={->,>=stealth, thick, draw=black!50}
]

\node (research) {Research design};
\node (traditional) [below left=of research] {Traditional class};
\node (flipped) [below right=of research] {Flipped class};
\node (pretest) [below=of research, text width=5cm, align=center, fill=white] {Pre-test algebra proficiency\\ Pre-test self-efficacy};
\node (training) [right=of flipped, xshift=-1cm, text width=3cm, align=center, fill=white] {Training sessions on flipped approach};
\node (traditional_lessons) [below=of traditional] {Traditional lessons};
\node (flipped_lessons) [below=of flipped] {Flipped lessons};
\node (survey) [right=of flipped_lessons, xshift=-1cm, text width=3cm, align=center, fill=white] {Post-treatment survey};
\node (posttest) [below=of pretest, text width=5cm, align=center, fill=white] {Post-test algebra proficiency\\ Post-test self-efficacy};
\node (interview) [below=of posttest, text width=4cm, align=center, fill=white] {Teacher interview};

% Arrows
\draw[pre] (research) -- (traditional);
\draw[pre] (research) -- (flipped);
\draw[pre] (traditional) -- (pretest);
\draw[pre] (flipped) -- (pretest);
\draw[pre] (flipped) -- (training);
\draw[pre] (training) |- (pretest);
\draw[pre] (pretest) -- (traditional_lessons);
\draw[pre] (pretest) -- (flipped_lessons);
\draw[post] (flipped_lessons) -- (survey);
\draw[pre] (traditional_lessons) -- (posttest);
\draw[pre] (flipped_lessons) -- (posttest);
\draw[pre] (posttest) -- (interview);

% Text Annotations
\node at ($(pretest) + (-4, 0)$) {Weeks 1 + 2};
\node at ($(traditional_lessons) + (-4, 0)$) {Weeks 3 to 8};
\node at ($(posttest) + (4, 0)$) {Week 9};

\end{tikzpicture}

\end{document}
 

\documentclass{article}
\usepackage{tikz}
\usepackage{amsmath}

\begin{document}

\begin{tikzpicture}[
    node distance=1.5cm and 2.5cm,
    every node/.style={draw, rectangle, align=center, rounded corners},
    pre/.style={->,>=stealth',thick,draw=black!50},
    post/.style={->,>=stealth',thick,draw=black!50}
]

\node (research) [text width=4cm, fill=white] {Research design};
\node (traditional) [below left=of research, text width=3cm, fill=blue!20] {Traditional class};
\node (flipped) [below right=of research, text width=3cm, fill=blue!20] {Flipped class};
\node (pretest) [below=of research, text width=5cm, fill=white] {Pre-test algebra proficiency\\ Pre-test self-efficacy};
\node (training) [right=of flipped, xshift=-1cm, text width=3cm, fill=white] {Training sessions on the flipped approach};
\node (traditional_lessons) [below=of traditional, text width=3cm, fill=blue!20] {Traditional lessons};
\node (flipped_lessons) [below=of flipped, text width=3cm, fill=blue!20] {Flipped lessons};
\node (survey) [right=of flipped_lessons, xshift=-1cm, text width=3cm, fill=white] {Post-treatment survey};
\node (posttest) [below=of pretest, text width=5cm, fill=white] {Post-test algebra proficiency\\ Post-test self-efficacy};
\node (interview) [below=of posttest, text width=4cm, fill=white] {Teacher interview};

% Arrows
\draw[pre] (research) -- (traditional);
\draw[pre] (research) -- (flipped);
\draw[pre] (traditional) -- (pretest);
\draw[pre] (flipped) -- (pretest);
\draw[pre] (flipped) -- (training);
\draw[pre] (training) -- ++(0, -2) -| (pretest);
\draw[pre] (pretest) -- (traditional_lessons);
\draw[pre] (pretest) -- (flipped_lessons);
\draw[post] (flipped_lessons) -- (survey);
\draw[pre] (traditional_lessons) -- (posttest);
\draw[pre] (flipped_lessons) -- (posttest);
\draw[pre] (posttest) -- (interview);

% Text Annotations
\node at ($(pretest) + (-4, 0)$) {Weeks 1 + 2};
\node at ($(traditional_lessons) + (-4, 0)$) {Weeks 3 to 8};
\node at ($(posttest) + (4, 0)$) {Week 9};

\end{tikzpicture}

\end{document}