Cross Sectional and Longitudinal Methods of Research Cross sectional and longitudinal studies are two different types of research design often used in developmental psychology. In a cross-sectional study you collect data from a population at a specific point in time; in a longitudinal study you repeatedly collect data from the same sample over an extended period of time. Cross Sectional Studies Observations at a single point in time Observes different groups (“a cross section”) Provides snapshot of society at a given point Pros: Quick, can get a larger sample Longitudinal Studies Repeated observations Observes the same group multiple times Follows changes in participants over time Pros: Detailed, effective in determining cause and effect Cons: Restricted to 1 point in time, cohort Cons: Expensive, takes a long time and effects (can’t apply to all population) drop outs Questions: Which research design (cross sectional or longitudinal) is depicted in each of the following examples? 1. A study of changes in intelligence over adulthood that examines intellectual abilities in the same 1,500 individuals each decade from ages 50 to 80 years. Ans: Longitudinal Studies 2. An examination of childhood changes in social development that representatively samples and then compares 18,000 participants assigned to groups of 4-, 8-, and 12-year-olds. Ans: Cross Sectional studies 3. An investigation of changes in physical development in infancy by comparing the progression of fine and gross motor skills in 22,000 infants of different ages, ranging from 2 months through 22 months. Ans: Cross Sectional 4. A study of changes every 20 years in political attitudes (liberal vs. conservative) over a 40-year span in 3,000 adults between the ages of 25 and 65 years. Ans: Longitudinal Below is a graph depicting the results of a cross-sectional study investigating the desensitisation of graphic health warning labels and their impact on smokers and non-smokers Answer the following questions using the graph from a cross-sectional study: 5. Which emotion did most respondents choose? Answ: disgust 6. What percentage of the respondents in the non-smoking category reported that they would avoid smoking because of the health warning labels? Ans: 70% 7. What is the percent difference between the non smokers and smokers when it comes the to feeling of fear in relation to the health warning labels? Why? Ans: The difference is 30%, reason being is smokers no longer feel fear from smoking and it’s consequences as they have become addicted while non-smokers are still scared as they haven’t experienced smoking yet. Answer the following questions using the graph of a the first longitudinal study on human growth. The father recording his son’s growth every 6 months until his 18th birthday. 8. Estimate the son’s height at 7 years old? Ans: Around 130-ish 9. Why do you think there is a gap in data between 11 and 12 years old? Ans: Most people’s growth spurts happen around this time 10. From the data collected what is the proposed “cause and effect”? Ans: Cause is age and effect is Height 11. Cynthia would like to learn about depression in high school students. Which type of research method would you use? Design and then briefly describe the research project using your chosen method. Some questions to consider: How will you get your information? What variables are being tested? Who will be part of your research? What questions are being asked? Etc.) Ans: Longitudinal seems to be a good method, as we try to find what is the cause of depression during school. The research should start at the beginning of the year, then the research ends once the school year ends. A group of 8th , 9th, 10th, 11th and especially 12th graders. These groups of students are to be questioned at the start of every semester and the end of every semester, to see how they are feeling before classes and after their classes after many projects, work, tests and everything else, especially at the end of the final semester. Some questions to ask: how do you feel about starting a new semester? Looking back at your semester now, how bad or good did it go for you? Are you feeling exhausted, relieved, happy, sad, anything now that the class is done? Did you feel that your assignments, tests, and projects were fair for you?
