Selecting Statistics

Number of variables in hypothesis Type of variable A (independent or predictor variable) Type of variable B (dependent or criterion variable) Between or within subjects design? Number of levels of independent or predictor variable? Test statistic Sample hypothesis

one N/A qualitative (or categorical) Between Any Chi square Psychology majors are more likely to be females than males

One N/A quantitative (or continuous) Between N/A One sample t-test Undergraduate students, on average, are over 17 years old

Two qualitative qualitative Between Any Chi square Psychology majors are more likley to be females than males, while physics majors are more likely to be males than females

Two quantitative quantitative Between N/A Correlation The more chocolate people eat, the happier they are

Two qualitative quantitative Between two Independent samples t-test People who eat chocolate every day are happier than people who never eat chocolate

Two qualitative quantitative Within two Paired samples t-test People have lower levels of depression after they've gone to therapy than they have before going to therapy

Two qualitative quantitative Between More than two ANOVA Psychology majors are happier than physics majors, who are happier than chemistry majors

Two qualitative quantitative Within More than two ANOVA People are happier in the fall than they are in the summer; people are happier in the summer than they are in the winter

More than two qualitative quantitative Any Any ANOVA People have more energy when they drink coffee than they have when they don't drink coffee, especially if they have slept 8 hours than night before. (an interaction)

Number of variables in hypothesis	Type of variable A (independent or predictor variable)	Type of variable B (dependent or criterion variable)	Between or within subjects design?	Number of levels of independent or predictor variable?	Test statistic	Sample hypothesis
one	N/A	qualitative (or categorical)	Between	Any	Chi square	Psychology majors are more likely to be females than males
One	N/A	quantitative (or continuous)	Between	N/A	One sample t-test	Undergraduate students, on average, are over 17 years old
Two	qualitative	qualitative	Between	Any	Chi square	Psychology majors are more likley to be females than males, while physics majors are more likely to be males than females
Two	quantitative	quantitative	Between	N/A	Correlation	The more chocolate people eat, the happier they are
Two	qualitative	quantitative	Between	two	Independent samples t-test	People who eat chocolate every day are happier than people who never eat chocolate
Two	qualitative	quantitative	Within	two	Paired samples t-test	People have lower levels of depression after they've gone to therapy than they have before going to therapy
Two	qualitative	quantitative	Between	More than two	ANOVA	Psychology majors are happier than physics majors, who are happier than chemistry majors
Two	qualitative	quantitative	Within	More than two	ANOVA	People are happier in the fall than they are in the summer; people are happier in the summer than they are in the winter
More than two	qualitative	quantitative	Any	Any	ANOVA	People have more energy when they drink coffee than they have when they don't drink coffee, especially if they have slept 8 hours than night before. (an interaction)