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Lakens / simulatePOWERdistributions
Created December 21, 2014 13:21
Simulate Power Distributions
library(MBESS)
library(pwr)
nSims <- 100000 #number of simulated experiments
p <-numeric(nSims) #set up empty container for all simulated p-values
obs_pwr <-numeric(nSims) #set up empty container
t <-numeric(nSims) #set up empty container
d_all<-numeric(nSims)
N<-33 #number of participants
@Lakens
Lakens / p_not_evidence.R
Created November 22, 2021 19:38
Why p-values are not measures of evidence
library(metafor)
g <- escalc(
measure = "SMD",
n1i = 43, # sample size in group 1 is 50
m1i = 1.3, # observed mean in group 1 is 5.6
sd1i = 1, # observed standard deviation in group 1 is 1.2
n2i = 43, # sample size in group 2 is 53
m2i = 1, # observed mean in group 1 is 4.9
sd2i = 1
@Lakens
Lakens / welch_student.R
Last active September 29, 2021 18:46
welch_student.R
require(car) #Car package required for Levene's test
n1<-38 #size condition x
n2<-22 #size condition y
sd1<-1.11 #sd condition x
sd2<-1.84 #sd condition y
m1<-0
m2<-0
trueD<-(m2-m1)/(sqrt((((n1 - 1)*((sd1^2))) + (n2 - 1)*((sd2^2)))/((n1+n2)-2)))
trueD
@Lakens
Lakens / MetaAnalyticThinking.R
Last active April 23, 2021 02:38
People find it difficult to think about random variation. Our mind is more strongly geared towards recognizing patterns than randomness. In this blogpost, you can practice with getting used to what random variation looks like, how to reduce it by running well-powered studies, and how to meta-analyze multiple small studies.
# # # # # # # # # # #
#Initial settings----
# # # # # # # # # # #
if(!require(ggplot2)){install.packages('ggplot2')}
library(ggplot2)
if(!require(MBESS)){install.packages('MBESS')}
library(MBESS)
if(!require(pwr)){install.packages('pwr')}
library(pwr)
if(!require(meta)){install.packages('meta')}
@Lakens
Lakens / Meta-Analysis in R
Created August 24, 2014 07:06
Perform a meta-analysis in R
#Script based on Carter & McCullough (2014) doi: 10.3389/fpsyg.2014.00823
#Load Libraries
library(meta)
library(metafor)
#Insert effect sizes and sample sizes
es.d<-c(0.38,0.41,-0.14,0.63,0.22)
n1<-c(75,48,22,18,60)
n2<-c(75,52,21,20,55)
@Lakens
Lakens / segmented_vs_sequential.R
Created August 29, 2020 07:49
Segmented vs. Sequential Analyses
library(segHT)
library(rpact)
looks <- 3
n_seg <- 50
alpha_level <- 0.05
true_d <- 0.5 # can not enter 0, segmented_hyp_test_outcomes gives error
###############################
# Segmented procedure ----
---
title: "Power Analysis for Interactions"
author: "Daniel Lakens"
date: "28-3-2020"
output:
html_document: default
pdf_document: default
word_document: default
editor_options:
chunk_output_type: console
@Lakens
Lakens / plot_single_pvalue_over_time.R
Created January 11, 2020 21:48
plot single p-value over time
n<-2000 #total number of datapoints (per condition) you are willing to collect after initial 10
D<-0.0 #True effect size (Keep SD below to 1, otherwise, this is just mean dif, not d)
SD<-1 #Set True standard deviation.
p<-numeric(n) #store p-values
x<-numeric(n) #store x-values
y<-numeric(n) #store y-values
n<-n+10 #script calculates p-values after 10 people in each condition, so add 10 to number of datapoints
@Lakens
Lakens / sim_study_scienceverse_2.R
Created March 12, 2020 09:21
scienceverse example for family-wise error control v2
# Scienceverse Sim
# install scienceverse
# devtools::install_github("scienceverse/scienceverse")
library(scienceverse)
library(faux)
set.seed(2) # set.seed(2) is a random draw where H1 is corroborated.
@Lakens
Lakens / sim_study_scienceverse_1.R
Created March 12, 2020 09:20
scienceverse example for family-wise error control v1
# Scienceverse Sim
# install scienceverse
# devtools::install_github("scienceverse/scienceverse")
library(scienceverse)
library(faux)
set.seed(2) # set.seed(2) is a random draw where H1 is corroborated.