Background
In a Stroop task, participants are presented with a list of words, with each word displayed in a color of ink. The participant’s task is to say out loud the color of the ink in which the word is printed. The task has two conditions: a congruent words condition, and an incongruent words condition. In the congruent words condition, the words being displayed are color words whose names match the colors in which they are printed: for example RED, BLUE. In the incongruent words condition, the words displayed are color words whose names do not match the colors in which they are printed: for example PURPLE, ORANGE. In each case, we measure the time it takes to name the ink colors in equally-sized lists. Each participant will go through and record a time from each condition. The dataset used for this project can be downloaded from this link
Data Exploration
Independent and Dependent Variables
The independent variable is the whether the condition is congruent or incongruent. The dependent variable is the time required to name the color in each condition.
Descriptive Statistics
For the congruent condition, the mean and the variance of times measured are 14.05 and 3.56 respectively. For the incongruent condition, the mean and the variance of times measured are 22.06 and 4.8 respectively.
Hypothesis Testing
Null and Alternate Hypotheses
H_0:The time required to identify the color in incongruent condition is equal to that in the congruent condition. H_A:The time required to identify the color in incongruent condition is different than that in the congruent condition.
Statistical test
H_0: μ_congruent= μ_incongruent
H_A: μ_congruent≠ μ_incongruent
t_critical=2.069 for 23 degrees of freedom at level of confidence α=0.05
s_D=4.86
t=μ_D/(s_D⁄√n)=7.96/(4.86⁄√24)=8.02
Since t>t_critical, we reject the null hypothesis. Hence, the time required to identify the color in congruent and incongruent conditions are not equal.
Visualization
The above chart shows that the time required to name a color in incongruent condition is always more than that in congruent condition.
The above chart is the histogram of the time required to identify color in incongruent condition.
The above chart is the histogram of the time required to identify color in congruent condition.
Author
The above project was done as part of the 'Data Analayst Nanodegree' by Roshan Shetty. Please contact me on rosshanabshetty@gmail.com for any doubts, queries or information.