Hypotheses, Variables and Sampling Methods
How psychologists plan a study: writing an aim and a null or alternative hypothesis, choosing the independent, dependent and extraneous variables, and picking participants by random, opportunity, systematic or stratified sampling.
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Planning a study 🧠
Before psychologists run a study, they plan it carefully. They write an aim and a hypothesis, decide which variables to change and measure, and choose how to pick their participants. This module covers hypotheses, variables and sampling methods. Getting these right makes a study fair and its results trustworthy.
Key words 🔑
Learn these four terms before you study how research is planned.
Two kinds of hypothesis 🆚
A study states two hypotheses about its variables.
Grade 9 thinking 💡
To reach the top grades, operationalise your variables, which means writing them so they can be measured. For example, do not just say sleep; say hours of sleep per night. Always be able to point to the independent variable you change and the dependent variable you measure.
Match the term 🔗
- independent variable
- dependent variable
- extraneous variable
- null hypothesis
- the variable the researcher changes
- the variable the researcher measures
- an unwanted variable that could affect the results
- the prediction that there is no difference
Match the sampling method 🧩
- random sampling
- opportunity sampling
- systematic sampling
- stratified sampling
- every member of the population has an equal chance of being chosen
- the people who are available at the time are used
- every nth person on a list is chosen
- subgroups are chosen in proportion to the population
Find the variable ❓
A researcher tests whether students who revise with music score differently on a test. What is the independent variable?
- Whether the students revise with music or without it.
- The scores the students get on the test.
- The number of students in the study.
A good hypothesis ✅
An alternative hypothesis does TWO of these things. Select the TWO.
- It predicts a difference or a relationship between the variables.
- It is a clear statement that can be tested.
- It lists every participant by name.
- It proves the results before the study begins.
Draw a sample 🪜
An interactive activity.
Complete the sentences 📝
The variable the researcher changes is the _____ variable. The variable the researcher measures is the _____ variable. An unwanted variable that could affect the results is an _____ variable. A hypothesis that predicts no difference is the _____ hypothesis. Choosing people so that every member of the population has an equal chance is _____ sampling.
Count the methods 🔢
An interactive activity.
Tap the variables 🖍️
An interactive activity.
Name the variable 🧭
An interactive activity.
Plan a study ✍️
An interactive activity.