Graphique en forêt de méta-analyse

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
from matplotlib.transforms import blended_transform_factory
from scipy import stats
from statsmodels.stats.meta_analysis import combine_effects

# Teacher-expectancy experiments (Raudenbush, 1984): standardised mean difference
# in pupil IQ (yi) and its sampling variance (vi), as in metafor's dat.raudenbush1985
pyg = pd.DataFrame({
    "study": ["Rosenthal et al. 1974", "Conn et al. 1968", "Jose & Cody 1971",
              "Pellegrini & Hicks 1972a", "Pellegrini & Hicks 1972b", "Evans & Rosenthal 1969",
              "Fielder et al. 1971", "Claiborn 1969", "Kester 1969", "Maxwell 1970", "Carter 1970",
              "Flowers 1966", "Keshock 1970", "Henrikson 1970", "Fine 1972", "Grieger 1970",
              "Rosenthal & Jacobson 1968", "Fleming & Anttonen 1971", "Ginsburg 1970"],
    "yi": [0.03, 0.12, -0.14, 1.18, 0.26, -0.06, -0.02, -0.32, 0.27, 0.80, 0.54, 0.18, -0.02,
           0.23, -0.18, -0.06, 0.30, 0.07, -0.07],
    "vi": [0.0156, 0.0216, 0.0279, 0.1391, 0.1362, 0.0106, 0.0106, 0.0484, 0.0269, 0.0630,
           0.0912, 0.0497, 0.0835, 0.0841, 0.0253, 0.0279, 0.0193, 0.0088, 0.0303]})
res = combine_effects(pyg.yi, pyg.vi, method_re="dl", row_names=pyg.study)
tab = res.summary_frame()
studies, pooled = tab.iloc[:len(pyg)], tab.loc["random effect"]
q_p = stats.chi2.sf(res.q, res.df_resid)

fig, ax = plt.subplots(figsize=(8, 7.6))
y = np.arange(len(pyg), 0, -1) + 1.0
ax.hlines(y, studies.ci_low, studies.ci_upp, color="#3A3A3C", lw=1.2)
ax.scatter(studies.eff, y, marker="s", s=900 * studies.w_re, color="#007AFF", zorder=3)

# Pooled random-effects diamond
lo, mid, hi = pooled.ci_low, pooled.eff, pooled.ci_upp
ax.fill([lo, mid, hi, mid], [0.5, 0.85, 0.5, 0.15], color="#FF9500", zorder=3)
ax.vlines(0, -0.2, len(pyg) + 1.5, color="#8E8E93", lw=1)
ax.vlines(mid, -0.2, len(pyg) + 1.5, color="#FF9500", lw=1, ls="--", zorder=1)

# Table columns to the right of the plot: d [95% CI] and weight
tr = blended_transform_factory(ax.transAxes, ax.transData)
for x, head in [(1.04, "d [95% CI]"), (1.36, "Weight")]:
    ax.text(x, len(pyg) + 2, head, transform=tr, fontsize=9.5, fontweight="semibold", va="center")
for yi, (_, r) in zip(y, studies.iterrows()):
    ax.text(1.04, yi, f"{r.eff:.2f} [{r.ci_low:.2f}, {r.ci_upp:.2f}]".replace("-", "−"),
            transform=tr, fontsize=9, va="center", color="#3A3A3C")
    ax.text(1.36, yi, f"{100 * r.w_re:.1f}%", transform=tr, fontsize=9, va="center", color="#3A3A3C")
for x, txt in [(1.04, f"{mid:.2f} [{lo:.2f}, {hi:.2f}]".replace("-", "−")), (1.36, "100%")]:
    ax.text(x, 0.5, txt, transform=tr, fontsize=9, va="center", fontweight="semibold")

ax.set_xlim(-1.0, 2.0)
ax.set_yticks(list(y) + [0.5], list(pyg.study) + ["Random effects (DL)"])
ax.get_yticklabels()[-1].set_fontweight("semibold")
ax.set_ylim(-0.2, len(pyg) + 2.6)
ax.grid(False); ax.spines["left"].set_visible(False)
ax.set_xlabel("Standardised mean difference in IQ, expectancy vs control (d)")
ax.text(-0.05, len(pyg) + 2, r"$\leftarrow$ control higher", ha="right", va="center", fontsize=9, color="#6E6E73")
ax.text(0.05, len(pyg) + 2, r"'bloomers' higher $\rightarrow$", ha="left", va="center", fontsize=9, color="#6E6E73")
ax.tick_params(axis="y", labelcolor="#1D1D1F")
ax.set_title(f"Teacher expectations shift pupils' IQ by only d = {mid:.2f} on average — "
             "and studies disagree", pad=26)
ax.text(0, 1.02, f"Pooled d = {mid:.2f} [{lo:.2f}, {hi:.2f}] · Q({res.df_resid:.0f}) = "
        f"{res.q:.1f}, p = {q_p:.3f} · I² = {100 * res.i2:.0f}% · τ² = {res.tau2:.3f} · k = {len(pyg)}",
        transform=ax.transAxes, fontsize=9.5, color="#6E6E73")
plt.show()