PSYC2010 - Lecture 2

What are the two ways to represent a a conceptual or statistical hypothesis?

• Null hypothesis (H0)

• Alternative hypothesis (H1)

What are the two different types of hypotheses?

• Conceptual hypotheses

• Statistical hypotheses

What is a conceptual hypothesis?

Outlines the qualitative predicted relationship between the Independent Variable and the Dependent Variable

• e.g H0: There is not a significant difference between the dependant variable and independent variable, H1: There is a significant difference between the dependant variable and independent variable

What is a statistical hypothesis?

Represents the predicted quantitative mathematical relationship between two or more population parameters

• e.g. H0: μ = 100, H1: μ ≠ 100

Define the null hypothesis (H0)

Predicting that there is no relation between the two variables we are investigating

Define the Alternative hypothesis (H1)

Predicting that there is a relationship between the two variables we are investigating

What is the sampling distribution of the mean?

A hypothetical distribution of infinite sample means from a given population, each of which have their own mean and SD, resulting in a mean equal to the population mean

What is the Central Limit Theorem?

Highlights that the sampling distribution of the mean will be normally distributed (bell curve) if the sample size is atleast 30

What is the Standard Error of the Mean (SEM / σx̄)?

The standard error of the mean is the standard deviation of the distribution of sample means.

• This represents the average distance between a sample mean and population mean

What is the critical z-score?

The critical z-score of +- 1.96 helps determine whether a dependant variable has had a significant difference in a two-tailed test

What happens when the Z-Score is greater than +1.96 or lower than -1.96?

It means the Z-Score is significant and we must reject the null hypothesis (H0), accept the Alternative Hypothesis (H1)

What happens when the Z-Score is lower than +1.96 or greater than -1.96?

We accept the null hypothesis (H0) and reject the alternative hypothesis (H1) as the Z-Score is not significant

What is a Z-test?

A formula depicting the ratio of observed to expected differences between the sample and population

What are the steps for conducting a single sample z-test?

1. State the hypotheses (H0 & H1) conceptually and statistically

2. Calculate the standard error of the mean

3. Calculate the Z-score

4. Make a decision comparing Z-score obtained to Z-score crucial value

5. Interpret your result

What is a t-test?

How do you conduct a one sample t-test?

When do you conduct a Z-Test?

If population mean and population SD are known

When do you conduct a t-test?

If only population mean is known

How do you calculate standard deviation?

How do you calculate sums of squares?