# 08. Two-Group Design

## Video: Independent-Samples t-test (SPSS for Beginners)

Video (8:11) from Research by Design and Dr. Todd Daniel, described as follows, “Another way of measuring the difference between two samples is to compare two unrelated groups or participants or samples. In this design, you measure two groups one time; in contrast, the previous paired test measured the same sample two times. With independent

## Video: How to Do an Independent Samples t Test in JASP

Video (18:29) from Research by Design in which, “Using a dataset about puppy training, we learn how to set up and run an independent samples t test. We import data into JASP, conduct the test, interpret the results and write up the findings. We will learn to check the assumptions of homogeneity of variance using

## Practice: t-test for Independent Means

In this activity, students will take data from a fictitious two-group design to practice conducting a t-test for Independent Means. First, provide students with the research scenario and the accompanying questions to have them determine the research design, statistical analysis to use, and independent and dependent variables. Next, have students set up a data file

## Assignment: t-test for Independent Means/Samples (SPSS)

In this assignment (created by Dr. Kimberly A. Barchard and Dr. Leiszle Lapping-Carr), students learn how to use SPSS to compare two independent groups using the independent samples t-test and using confidence intervals for the difference of the means. Students also write a research report with their results. A detailed grading rubric is included. This

## Tutorial: t-test for Independent Means/Samples (WISE)

Online tutorial that guides students through a research study and data analysis using a t-test for independent means/samples. This particular study compares differences in child rearing practices in Belize and Samoa. During the tutorial students will need to review data for data entry errors, look at descriptive statistics, form a hypothesis, perform the statistic, and

## Lab Activity: How Does Novelty Impact Food Enjoyment? (t-test for Independent Means/Samples)

In this activity (created by Dr. Eliane Boucher), students will participate in a simplified version of the first study conducted by O’Brien and Smith (2019). In this study, participants were instructed to eat a familiar food (popcorn) in a conventional or an unconventional way (with chopsticks). Participants then rated how enjoyable the food was (note

## Exemplar Study: Tipping in Restaurants (Two-group Design/Simple Experiment)

To evaluate the effect that a helpful message from a server might have on restaurant tips, the server either wrote a message about an upcoming dinner special on the back of the dining check or left it blank. Dining parties who received a check with the helpful message tipped a higher percentage of the final

## Practice: Calculating the t-test for Independent Samples/Means (Temperature and Mood)

Instructors should assign this problem (about how temperature impacts mood) to students as in-class practice or homework after students have learned how to calculate a t-test for independent means and test for significance. The activity leads students through determining the type of statistical analysis to use, the hypotheses, calculating the t-ratio and effect size (if

## Practice: Calculating the t-test for Independent Samples/Means (Research Methods and GPA)

Instructors should assign this problem (about how taking research methods impacts GPA) to students as in-class practice or homework after students have learned how to calculate a t-test for independent means and test for significance. The activity leads students through determining the type of statistical analysis to use, the hypotheses, calculating the t-ratio and effect

## Lecture Slides: Calculating the t-test for Independent Means/Samples (Does Eating Spinach Make Your Stronger?)

The goal of this PowerPoint is to work through the step-by-step process of hand calculating a t-test for independent means. The slides start with an explanation of the formula involved and then a sample problem is presented. It is designed for you to have the class solve the problem along with you as you advance

## Lecture Slides: Arousal and Attraction (Two-Group Design Demonstration)

In this demonstration/activity (with PowerPoint slides) students are randomly assigned to a high or low arousal group based on the last digit of their social security number. Those in high arousal condition believe they will give a short speech on a randomly selected topic. Those in low arousal condition believe they will merely listen a

## Design & Data: Texting, I Can’t Get You Out of My Mind (Two-Group Design and t-test for Independent Means/Samples)

Key Topics and Links to Files Data Analysis Guide Texting: I Can’t Get You Out of My Mind Analyses Included: t-test for Independent Means Dataset Syntax Output BONUS: How Does the Experience of Stress Influence Feelings toward One’s Relationship? Analyses Included: t-test for Independent Means; Creating a Mean; Reliability (Cronbach’s alpha)  Dataset Syntax Output The

## Open Stats Lab: t-test Activities

Activities focus on the following topics: (SINGLE SAMPLE and PAIRED-SAMPLES) Does Music Convey Social Information to Infants? Here students get to conduct a single/one sample t-test, a t-test for dependent means (paired samples), and can create a boxplot and/or scatterplot. (TWO INDEPENDENT SAMPLES) Do Spoken or Written Words Better Express Intelligence? Here students get to

## Exemplar Study: Smells Like Clean Spirit (Two-group Design/Simple Experiment)

In three studies, the authors examined unconscious influence of smell on behavior. Study 3 used a two-group design to examine the direct effect of citrus scent (exposed vs. nonexposed) on cleaning-related behaviors. The judges recorded the frequency of participants’ crumb removal while eating. Holland, R. W., Hendriks, M., & Aarts, H. (2005). Smells like clean