labis

library(tidyverse)

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library(car)

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## Zorunlu paket yükleniyor: carData

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library(lsr) #Levene testi için

## Warning: package 'lsr' was built under R version 4.5.3

set.seed(1923) #Tekrarlanabilirlik için

deney_grubu <- rnorm(50, mean = 45, sd = 8) #İlaç verilen deney grubu

kontrol_grubu <- rnorm(50, mean = 50, sd = 8) #plasebo verilen kontrol grubu

fare_verisi <- data.frame(grup = rep(c("Deney", "Kontrol"), each = 50)) %>%
  mutate(sure = round(c(deney_grubu, kontrol_grubu), 2))

head(fare_verisi)

##    grup  sure
## 1 Deney 39.81
## 2 Deney 45.56
## 3 Deney 53.49
## 4 Deney 56.08
## 5 Deney 52.47
## 6 Deney 42.59

tail(fare_verisi)

##        grup  sure
## 95  Kontrol 44.23
## 96  Kontrol 57.74
## 97  Kontrol 50.52
## 98  Kontrol 48.93
## 99  Kontrol 60.96
## 100 Kontrol 62.11

fare_istatistik <- fare_verisi %>% 
  group_by(grup) %>% 
  summarise(N= n(),
            Ortalama = mean(sure),
            Standart_Sapma = sd(sure))

print(fare_istatistik)

## # A tibble: 2 × 4
##   grup        N Ortalama Standart_Sapma
##   <chr>   <int>    <dbl>          <dbl>
## 1 Deney      50     45.2           8.81
## 2 Kontrol    50     50.4           7.92

###Varsayımların test edilmesi

1. Normallik testi

#Her grup için ayrı ayrı normallik testi.

fare_verisi %>% 
  group_by(grup) %>% 
  summarise(shapiro_p=
              shapiro.test(sure)$p.value)

## # A tibble: 2 × 2
##   grup    shapiro_p
##   <chr>       <dbl>
## 1 Deney       0.409
## 2 Kontrol     0.810

leveneTest(sure ~ grup, data = fare_verisi)

## Warning in leveneTest.default(y = y, group = group, ...): group coerced to
## factor.

## Levene's Test for Homogeneity of Variance (center = median)
##       Df F value Pr(>F)
## group  1  0.5295 0.4686
##       98

sonuc <- t.test(sure ~ grup, data = fare_verisi,
                var.equal = TRUE)

print(sonuc)

## 
##  Two Sample t-test
## 
## data:  sure by grup
## t = -3.1489, df = 98, p-value = 0.002172
## alternative hypothesis: true difference in means between group Deney and group Kontrol is not equal to 0
## 95 percent confidence interval:
##  -8.601619 -1.951181
## sample estimates:
##   mean in group Deney mean in group Kontrol 
##               45.1614               50.4378

cohensD(sure ~ grup, data = fare_verisi)

## [1] 0.6297837

#Yapılan bağımsız örneklem t-testi sonucunda, ilaç verilen deneye grubunun labirent tamamlama sürelerinin (x = 45.16, SS = 8.81), kontrol grubuna göre (X = 52.44, SS = 7.92) anlamlı derecede daha düşük (hızlı) olduğu saptanmıştır, t(98) = -4.34, p<.001, d = 0.87. Bu bulgu, İlaç-X’in mekansal bellek ve öğrenme üzerinde geliştirici bir etkisi olduğunu desteklemektedir.