def generate_t_distribution_chart_data(alpha, t_stat, n_1, n_2, x_bar_1, x_bar_2, s_1, s_2):
welches_df = utils.welches_degrees_of_freedom(s_1, n_1, s_2, n_2)
d = utils.calculate_cohens_d(x_bar_1, s_1, n_1, x_bar_2, s_2, n_2)
alpha_upper = t.ppf(1 - alpha/2, df=welches_df)
alpha_lower = -alpha_upper
# Determine X axis range
x_min = -5
x_max = 5
x_axis = list(np.arange(x_min, x_max, (x_max - x_min) / 501))
x_axis_values = ["{:.3f}".format(x) for x in x_axis]
H0 = []
significant = []
for value in x_axis:
H0.append(t.pdf(value, df=welches_df))
if alpha_lower <= value <= alpha_upper:
significant.append(None)
else:
significant.append(t.pdf(value, df=welches_df))
return {
"title": "t-statistic distribution (effect size: {:.3f})".format(d),
"xAxisLabel": "t",
"yAxisLabel": "Density",
"labels": x_axis_values,
"verticalLine": {
"position": "{:.3f}".format(utils.find_closest_value(x_axis, t_stat)),
"label": "t statistic: {:.3f}".format(t_stat)
},
"dataset": [
{
"label": "H0",
"data": H0,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[0],
"backgroundColor": None
},
{
"label": "H0",
"data": significant,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[0],
"backgroundColor": colors.background_colors[0]
}
]
}
def generate_p_value_vs_effect_size_chart_data(n_1, n_2, x_bar_1, x_bar_2, s_1, s_2, alpha):
d_raw = utils.calculate_cohens_d(x_bar_1, s_1, n_1, x_bar_2, s_2, n_2)
d_adjustment = utils.calculate_d_adjustment(s_1, n_1, s_2, n_2)
d_results = tt.calculate_min_effect_size(n_1=n_1, n_2=n_2, alpha=alpha, power=0.5)
d_target = d_results[1][0] / d_adjustment
ff = 0.5
if d_raw < 0:
x_min = min(-d_target, d_raw) * (1 + ff)
x_max = max(-d_target, d_raw) * (1 - ff)
else:
x_min = min(d_target, d_raw) * (1 - ff)
x_max = max(d_target, d_raw) * (1 + ff)
# Rounding to ensure matches
step = (x_max - x_min) / 500
dps = utils.determine_decimal_points(x_max)
effect_sizes = [round(x, dps) for x in np.arange(x_min, x_max, step)]
d_actual = utils.find_closest_value(effect_sizes, d_raw)
d_target = utils.find_closest_value(effect_sizes, d_target)
os_lower = []
ts_lower = []
os_higher = []
ts_higher = []
for d in effect_sizes:
welches_df = utils.welches_degrees_of_freedom(s_1, n_1, s_2, n_2)
t_stat = tt.calculate_t_stat_from_cohens_d(d, n_1, n_2) * d_adjustment
results = tt.calculate_p_value(t_stat, welches_df)
if d <= d_target:
os_lower.append(results[0][0])
ts_lower.append(results[1][0])
else:
os_lower.append(None)
ts_lower.append(None)
if d >= d_target:
os_higher.append(results[0][0])
ts_higher.append(results[1][0])
else:
os_higher.append(None)
ts_higher.append(None)
# Determine X axis range
format_string = "{:." + str(dps) + "f}"
x_axis_values = [format_string.format(x) for x in list(effect_sizes)]
return {
"title": "p-value vs Effect Size (sample size: {}, enrolment ratio: {:.3f})".format(n_1 + n_2, n_1/n_2),
"xAxisLabel": "Effect Size (d)",
"yAxisLabel": "p-value",
"labels": x_axis_values,
"verticalLine": {
"position": format_string.format(d_actual),
"label": "Effect Size: " + format_string.format(d_raw)
},
"dataset": [
{
"label": "One Sided Test",
"data": os_lower,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[0],
"backgroundColor": colors.background_colors[0]
},
{
"label": "One Sided Test",
"data": os_higher,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[1],
"backgroundColor": colors.background_colors[1]
},
{
"label": "Two Sided Test",
"data": ts_lower,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[0],
"backgroundColor": colors.background_colors[0]
},
{
"label": "Two Sided Test",
"data": ts_higher,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[1],
"backgroundColor": colors.background_colors[1]
}
]
}
def generate_p_value_vs_sample_size_chart_data(n_1, n_2, x_bar_1, x_bar_2, s_1, s_2, alpha):
d_actual = utils.calculate_cohens_d(x_bar_1, s_1, n_1, x_bar_2, s_2, n_2)
d_adjustment = utils.calculate_d_adjustment(s_1, n_1, s_2, n_2)
n_raw = n_1 + n_2
r_e = n_1 / n_2
n_results = tt.calculate_sample_size_from_means(mu_1=x_bar_1, mu_2=x_bar_2, sigma_1=s_1, sigma_2=s_2, alpha=alpha, power=0.5, enrolment_ratio=r_e)
n_target = n_results[0][1] + n_results[1][1]
ff = 0.1
x_min = int(max(4, min(n_raw * (1 - ff), n_target * (1 - ff))))
x_max = int(max(n_raw * (1 + ff), n_target * (1 + ff)))
step = int(max(1, (x_max - x_min) / 500))
sample_sizes = np.arange(x_min, x_max, step)
n_actual = utils.find_closest_value(sample_sizes, n_raw)
n_target = utils.find_closest_value(sample_sizes, n_target)
os_lower = []
ts_lower = []
os_higher = []
ts_higher = []
for n in sample_sizes:
cn_1 = math.ceil(n * r_e / (1 + r_e))
cn_2 = math.ceil(n - cn_1)
welches_df = utils.welches_degrees_of_freedom(s_1, cn_1, s_2, cn_2)
d = utils.calculate_cohens_d(x_bar_1, s_1, cn_1, x_bar_2, s_2, cn_2)
t_stat = tt.calculate_t_stat_from_cohens_d(d, cn_1, cn_2) * d_adjustment
results = tt.calculate_p_value(t_stat, welches_df)
if n <= n_target:
os_lower.append(results[0][0])
ts_lower.append(results[1][0])
else:
os_lower.append(None)
ts_lower.append(None)
if n >= n_target:
os_higher.append(results[0][0])
ts_higher.append(results[1][0])
else:
os_higher.append(None)
ts_higher.append(None)
# Determine X axis range
x_axis_values = [str(x) for x in list(sample_sizes)]
return {
"title": "Sample Size vs p-value (effect size: {:.3f}, enrolment ratio: {:.3f})".format(d_actual, n_1/n_2),
"xAxisLabel": "Total Samples",
"yAxisLabel": "p-value",
"labels": x_axis_values,
"verticalLine": {
"position": str(n_actual),
"label": "Sample Size: {}".format(n_raw)
},
"dataset": [
{
"label": "One Sided Test",
"data": os_lower,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[0],
"backgroundColor": colors.background_colors[0]
},
{
"label": "One Sided Test",
"data": os_higher,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[1],
"backgroundColor": colors.background_colors[1]
},
{
"label": "Two Sided Test",
"data": ts_lower,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[0],
"backgroundColor": colors.background_colors[0]
},
{
"label": "Two Sided Test",
"data": ts_higher,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[1],
"backgroundColor": colors.background_colors[1]
}
]
}
def generate_sampling_distributions_chart_data(mu_1, mu_2, sigma_1, sigma_2, n_1, n_2, alpha):
n = n_1 + n_2 - 2
df = utils.welches_degrees_of_freedom(sigma_1, n_1, sigma_2, n_2)
H0_mean = 0
HA_mean = mu_2 - mu_1
sd_pooled = utils.calculate_pooled_standard_deviation(n_1, n_2, sigma_1, sigma_2)
se = sd_pooled * (1/n_1 + 1/n_2)**0.5
d = utils.calculate_cohens_d(mu_1=mu_1, sigma_1=sigma_1, n_1=n_1, mu_2=mu_2, sigma_2=sigma_2, n_2=n_2)
nc = d * (2 / (1/n_1 + 1/n_2) / 2)**0.5
if mu_1 > mu_2:
nc *= -1
# Determine X axis range
x_min = min(H0_mean, nc) - 4
x_max = max(H0_mean, nc) + 4
x_axis_values = list(np.linspace(start=x_min, stop=x_max, num=1000, endpoint=True))
alpha_lower = t.ppf(q=alpha/2, df=df)
alpha_upper = -1 * alpha_lower
# Insert key values
for val in [H0_mean, nc, alpha_lower, alpha_upper]:
if val not in x_axis_values:
bisect.insort(x_axis_values, val)
H0_significant = []
H0_not_significant = []
HA_powered = []
HA_unpowered = []
threshold = alpha_upper if HA_mean >= H0_mean else alpha_lower
nct_dist = utils.initialize_nct_distribution(df=df, nc=nc)
for value in x_axis_values:
# Null Hypothesis
H0_not_significant.append(t.pdf(x=value, df=df))
if value < alpha_lower or value > alpha_upper:
H0_significant.append(t.pdf(x=value, df=df))
else:
H0_significant.append(None)
# Alternative Hypothesis
HA_powered.append(nct_dist.pdf(x=value))
if HA_mean < H0_mean and value > alpha_lower:
HA_unpowered.append(nct_dist.pdf(x=value))
elif HA_mean >= H0_mean and value < alpha_upper:
HA_unpowered.append(nct_dist.pdf(x=value))
else:
HA_unpowered.append(None)
if HA_mean < H0_mean:
power = nct_dist.cdf(x=alpha_lower)
threshold = alpha_lower
else:
power = 1 - nct_dist.cdf(x=alpha_upper)
threshold = alpha_upper
decimal_points = utils.determine_decimal_points(x_max)
format_string = "{:." + str(decimal_points) + "f}"
return {
"title": "Central and Noncentral Distributions (effect size: {:0.3f}, α: {:0.3f}, power (1 - β): {:.1%})".format(d, alpha, power),
"xAxisLabel": "t statistic",
"yAxisLabel": "Density",
"labels": [format_string.format(x) for x in x_axis_values],
"verticalLine": {
"position": format_string.format(utils.find_closest_value(x_axis_values, threshold)),
"label": "t crit: " + format_string.format(threshold)
},
"hidePoints": True,
"dataset": [
{
"label": "H0 - Significant",
"data": H0_significant,
"borderColor": colors.line_colors[0],
"backgroundColor": colors.background_colors[0]
},
{
"label": "H0",
"data": H0_not_significant,
"borderColor": colors.line_colors[0],
"backgroundColor": None
},
{
"label": "HA - Powered",
"data": HA_powered,
"borderColor": colors.line_colors[1],
"backgroundColor": None
},
{
"label": "HA",
"data": HA_unpowered,
"borderColor": colors.line_colors[1],
"backgroundColor": colors.background_colors[1]
}
]
}
def generate_power_vs_effect_size_data(d, alpha, power, n_1, n_2):
power_list = list(np.arange(0.4, 1, 0.001))
power_target = utils.find_closest_value(power_list, power)
os_lower = []
ts_lower = []
os_upper = []
ts_upper = []
for pow in power_list:
results = tt.calculate_min_effect_size(n_1=n_1, n_2=n_2, alpha=alpha, power=pow)
if pow < power_target:
os_lower.append(results[0][0])
ts_lower.append(results[1][0])
os_upper.append(None)
ts_upper.append(None)
elif pow > power_target:
os_lower.append(None)
ts_lower.append(None)
os_upper.append(results[0][0])
ts_upper.append(results[1][0])
elif pow == power_target:
os_lower.append(results[0][0])
ts_lower.append(results[1][0])
os_upper.append(results[0][0])
ts_upper.append(results[1][0])
return {
"title": "Power vs Effect Size (α: {:0.3f}, total samples: {})".format(alpha, n_1 + n_2),
"xAxisLabel": "Power (1 - β)",
"yAxisLabel": "Effect Size (d)",
"labels": ["{:.3f}".format(x) for x in power_list],
"verticalLine": {
"position": "{:.3f}".format(power_target),
"label": "Statistical Power: {:.3f}".format(power)
},
"dataset": [
{
"label": "One Sided Test",
"data": os_lower,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[0],
"backgroundColor": colors.background_colors[0]
},
{
"label": "One Sided Test",
"data": os_upper,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[1],
"backgroundColor": colors.background_colors[1]
},
{
"label": "Two Sided Test",
"data": ts_lower,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[0],
"backgroundColor": colors.background_colors[0]
},
{
"label": "Two Sided Test",
"data": ts_upper,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[1],
"backgroundColor": colors.background_colors[1]
}
]
}
def generate_sample_size_vs_effect_size_data(d, alpha, power, n_1, n_2):
enrolment_ratio = n_1/n_2
n_raw = n_1 + n_2
ff = 0.5
x_min = max(4, int(n_raw * (1 - ff)))
x_max = max(int(n_raw * (1 + ff)), 100)
step = int(max(1, (x_max - x_min) / 500))
sample_sizes = np.arange(x_min, x_max, step)
n_actual = utils.find_closest_value(sample_sizes, n_raw)
os_lower = []
ts_lower = []
os_upper = []
ts_upper = []
for n in sample_sizes:
cn_1 = math.ceil(n * enrolment_ratio / (1 + enrolment_ratio))
cn_2 = math.ceil(n - cn_1)
results = tt.calculate_min_effect_size(n_1=cn_1, n_2=cn_2, alpha=alpha, power=power)
if n < n_actual:
os_lower.append(results[0][0])
ts_lower.append(results[1][0])
os_upper.append(None)
ts_upper.append(None)
elif n > n_actual:
os_lower.append(None)
ts_lower.append(None)
os_upper.append(results[0][0])
ts_upper.append(results[1][0])
elif n == n_actual:
os_lower.append(results[0][0])
ts_lower.append(results[1][0])
os_upper.append(results[0][0])
ts_upper.append(results[1][0])
return {
"title": "Sample Size vs Effect Size (α: {:0.3f}, power (1 - β): {:.1%})".format(alpha, power),
"xAxisLabel": "Sample Size",
"yAxisLabel": "Effect Size (d)",
"labels": [str(x) for x in list(sample_sizes)],
"verticalLine": {
"position": str(n_actual),
"label": "Sample Size: {}".format(n_raw)
},
"dataset": [
{
"label": "One Sided Test",
"data": os_lower,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[0],
"backgroundColor": colors.background_colors[0]
},
{
"label": "One Sided Test",
"data": os_upper,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[1],
"backgroundColor": colors.background_colors[1]
},
{
"label": "Two Sided Test",
"data": ts_lower,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[0],
"backgroundColor": colors.background_colors[0]
},
{
"label": "Two Sided Test",
"data": ts_upper,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[1],
"backgroundColor": colors.background_colors[1]
}
]
}
def generate_effect_size_vs_power_chart_data(d, alpha, n_1, n_2):
ff = 0.1
d_powered = tt.calculate_min_effect_size(n_1=n_1, n_2=n_2, alpha=alpha, power=0.8)
if d < 0:
x_min = min(-d_powered[1][0], d) * (1 + ff)
x_max = max(-0.01, d * (1 + ff))
else:
x_min = min(0.01, d * (1 - ff))
x_max = max(d_powered[1][0], d) * (1 + ff)
step = (x_max - x_min) / 500
dps = utils.determine_decimal_points(x_max)
effect_sizes = [round(x, dps) for x in np.arange(x_min, x_max, step)]
d_actual = utils.find_closest_value(effect_sizes, d)
os_lower = []
ts_lower = []
os_higher = []
ts_higher = []
for es in effect_sizes:
results = tt.calculate_power_from_cohens_d(d=es, n_1=n_1, n_2=n_2, alpha=alpha)
if (es < d_actual and d_actual > 0) or (es > d_actual and d_actual < 0):
os_lower.append(results[0][0])
ts_lower.append(results[1][0])
os_higher.append(None)
ts_higher.append(None)
elif (es < d_actual and d_actual < 0) or (es > d_actual and d_actual > 0):
os_lower.append(None)
ts_lower.append(None)
os_higher.append(results[0][0])
ts_higher.append(results[1][0])
elif es == d_actual:
os_lower.append(results[0][0])
ts_lower.append(results[1][0])
os_higher.append(results[0][0])
ts_higher.append(results[1][0])
format_string = "{:." + str(dps) + "f}"
chart_data = {
"title": "Sample Size vs Effect Size (α: {:.3f}, total samples: {:,})".format(alpha, n_1 + n_2),
"xAxisLabel": "Effect Size (d)",
"yAxisLabel": "Statistical Power (1 - β)",
"labels": [format_string.format(es) for es in effect_sizes],
"verticalLine": {
"position": format_string.format(d_actual),
"label": "Effect Size: " + format_string.format(d)
},
"dataset": [
{
"label": "Lower Powers – One Sided Test",
"data": os_lower,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[0],
"backgroundColor": colors.background_colors[0]
},
{
"label": "Higher Powers – One Sided Test",
"data": os_higher,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[1],
"backgroundColor": colors.background_colors[1]
},
{
"label": "Lower Powers – Two Sided Test",
"data": ts_lower,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[0],
"backgroundColor": colors.background_colors[0]
},
{
"label": "Higher Powers – Two Sided Test",
"data": ts_higher,
"pointBorderWidth": 0,
"pointRadius": 0.5,
"borderColor": colors.line_colors[1],
"backgroundColor": colors.background_colors[1]
},
]
}
return chart_data
