W4 Flashcards
What does a two-sample hypothesis test ask?
Whether two groups have different means. The null hypothesis states that the sample means of the two groups cannot be distinguished.
Describe a between subjects design.
It involves two independent groups where each participant is assigned to only one group, providing one data point per participant. It’s also known as an Independent Measures design.
What are the pros and cons of a between subjects design?
Pros include shorter participation per individual and lower practice and order effects. Cons include individual differences, allocation of participants to groups, and the need for more participants.
Explain a within subjects design.
It involves two dependent groups where each participant completes two conditions, providing two data points per participant. It’s also known as a Repeated Measures design.
What are the pros and cons of a within subjects design?
Pros include removing individual differences and requiring fewer participants. Cons include practice and order effects and longer participation per individual.
How do you calculate an independent samples t-test?
Subtract the mean of group 2 from the mean of group 1, then divide by the pooled standard error of the mean.
What does it mean if the t-value of an independent samples t-test is large and positive? Large and negative? Near zero?
A large positive t-value indicates that the mean of group 1 is greater than the mean of group 2. A large negative t-value indicates the opposite. A t-value near zero suggests the means are indistinguishable.
What is Levene’s test used for?
It tests the homogeneity of variance between groups. A p-value greater than 0.05 indicates that the groups have equal variances.
When is Welch’s t-test used?
It’s used when groups have different variances. It calculates the difference between group means divided by the unpooled standard error of the difference.
What is a paired samples t-test?
It’s used to compare means of two dependent distributions.
How is a paired samples t-test calculated?
Subtract the mean of paired differences from zero, then divide by the standard error of the mean paired difference.
When do you use a t-test?
It’s used for comparing two group means or a single mean to a reference/comparison value when the data is interval or ratio type and assumptions are met.
