Independent Samples T test: For 2 Samples
What is the independent and dependent variable of the example below? Do women own more shoes than men?
IV: Women/Men DV: Amount of shoes
Do we want to reject the null in the case of homogeneity
No
Are smaller or larger samples better at estimating the population
larger
How do you calculate the degrees of freedom
df = n1 + n2 - 2
What do you need to know for obtaining the critical value
directional or non directional df alpha level
This research compares how many groups on a variable of interest
2
What distribution is associated with the dependent variable
A normal distribution
Homogeneity of Variance states that
Both variances are equal.
What are the assumptions of independent samples
Each value is sampled independently of each other Two populations are normally distributed Two populations must have equal variances. σ^21 = σ^22
What is the null hypothesis for a two tailed test (Non directional)
H0: mu 1 = mu 2
What is the null hypothesis for a one tailed test (Directional)
H0: mu 1 > or equal to mu 2 H0: mu 1 < or equal to mu 2
What is the alternative hypothesis for a one tailed test (Directional)
H1: mu 1 > mu 2 H1: mu 1 < mu 2
What is the alternative hypothesis for a two tailed test (Non directional)
H1: mu 1 is not equal to mu 2
Sampling fluctuation
How statistical values vary from sample to sample
Why is the estimated standard error equation biased
It's biased because it treats the variances equally when they are not
In the estimated standard error part of the t statistic formula, the M1 approximates
Mu 1 with some error and Mu 2 with some error.
Heterogeneity of variance states that
Samples are drawn from populations with different variances
Leptokurtosis
Sharpest peak
What is the assumption with estimated standard error equation
That n1 and n2 are equal.
Platykurtosis
The curve with a plateau
Mesokurtosis
The middle curve
Which hypothesis state that the variances are equal
The null
What does the alternative hypothesis state
The samples come from different populations
What does kurtosis mean?
The sharpness of a peak of a frequency-distribution curve
The null is saying that
The two samples from from the same population
If the samples come from different populations, that means
There is a difference between the two groups
If the two samples come from the same population
There is no significant difference
The two groups being studied have an equal
Variance
When does heterogeneity of variance occur
When one variance is 4 times more than the other and when variance and sample size are unequal
How do you decide which group is mu 1 or mu 2
Which ever one is said first is mu 1
n
the number of scores for the groups n1 = number of scores for group 1 n2 = number of scores for group 2
Pooled variance is the average of
the two sample variances
When do you use pooled varience
when n1 is not equal to n2