Introduction to Correlational Studies Mr.Krstovic

Part I) Introduction to Correlational Studies and Variables

An experiment is an activity in which one or more independent ('cause') variables are forced to change. For example, to test the effect of different types of soils on bean plant growth, we could conduct an experiment by using several types of soils (independent [‘cause’] variable) and measure how high the bean plant grows (dependent ['result'] variable).

Instead, we could find some bean plants in nature, measure their heights and examine the type of soil in each case. We can then see if there is a relationship between plant height and type of soil. This type of investigation would be a study, not an experiment. The independent ('cause') variable is allowed to change naturally . It also would be a correlational study, because we would be comparing (correlating) how changes in one variable (e.g., types of soil) may affect changes in another variable (e.g., plant height).

Correlational studies are useful when it’s not ethical to measure the changes in the result variable resulting from certain cause variables. With types of soil and bean plant growth it would be better to conduct an experiment anyways. However, if we wanted to study the relationship between smoking and people who develop lung cancer, then we would conduct a study. It’s not right (ethical) to force one group of people smoke and see if they develop lung cancer.

Exercises:

1) Using the following table, match each cause variable with its result variable. More than one possible answer can exist.

Cause Variables (Independent) Result Variables (Dependent) vegetarianism teenagers’ hearing rock music teenagers’ learning exercise plant height hormones growth of bacteria drugs aggressive behaviour T.V. watching physical fitness temperature muscle strength 2) How would you conduct the following investigations? Would you perform an experiment or conduct a study? Identify independent and dependent variables in each case (IV/DV). Also, think about what you would have to control!

a) The effect of smoking on respiratory (breathing) rate. Study Experiment I.V: D.V: Control(s):

b) Solubility of salt at various temperatures Study Experiment I.V: D.V: Control(s):

c) Amount of time spent playing video games and your grades in school Study Experiment I.V: D.V: Control(s):

d) The effect of different types of acids on corrosion (rusting) of metal Study Experiment I.V: D.V: Control(s):

e) The effect that gender (male/female) plays on the way shampoo ads and commercials are perceived Study Experiment I.V: D.V: Control(s):

f) Frequency of use of body lotions by high school students ages 14 to 18. Study Experiment I.V: D.V: Control(s): Part II) Sample Correlational Study

Question 1: Is there a correlation between gender and memory?

Sample Data Collection Table: All the boys and girls in a Grade 10 class were asked to view 10 random cards individually for 30 seconds. Then they had 1 minute to recall as many cards as they remember. The researcher recorded the correct number of cards recalled in the table below.

Gender # Cards Gender # Cards Memorized (max Memorized (max 10) 10) M 5 F 5 F 4 F 4 F 5 F 3 M 3 M 4 F 7 F 6 F 5 M 9 F 3 M 10 M 5 F 5 M 7 F 9 F 7 M 6 M 8 F 5 M 7 F 4 M 6 M 8 F 6 M 7 M 4 M 7

i. Total # of Males in the Study: ______

ii. Total # of Females in the Study: ______

iii. Average # of Cards Memorized by Males: ______

iv. Average # of Cards Memorized by Males: ______

v. Is there a correlation between gender and memory? Explain.

vi. How can we represent the above data visually?

vii. What are some factors that would affect our results?