Flashcards in Hypothesis Testing Deck (23):

1

## What are you asking when you do Hypothesis Testing?

### Is the hypothesis supported by facts (empirical data)?

2

## What is a Hypothesis?

### A prediction about the relationship between 2 variables that asserts that changes in the measure of an independent variable will correspond to changes in the measure of a dependent variable.

3

## We almost always test hypotheses using...

###
...sample data.

--> Draw conclusions about the population based on sample statistics

--> Therefore, always possible that any finding is due to sampling error

4

## Are the findings regarding our hypothesis "real" or due to sampling error?

###
-Is there a "statistically significant" finding?

-Therefore, also referred to as "significance testing"

5

## What is the Research Hypothesis?

###
H1

-Typically predicts relationships or "differences"

6

## What is the Null Hypothesis?

###
H0

-Predicts "no relationship" or "no difference"

-Can usually create by inserting "not" into a correctly worded research hypothesis

7

## What do we test in Science?

### The Null Hypothesis

8

## What is a Non-directional research hypothesis?

###
-"There was an effect"

-"There is a difference"

9

## What is a Directional research hypothesis?

### Specifies the direction of the difference (greater or smaller) from the H0

10

## What are the four main steps for Testing a Hypothesis?

###
1. State the null & research hypotheses

2. Set the criteria for a decision [Alpha, critical regions for particular test statistic]

3. Compute a "test statistic"

4. Make a decision

11

## What is a "test statistic"?

### A measure of how different finding is from what is expected under the null hypothesis.

12

## How do you make a decision while testing a hypothesis?

###
REJECT or FAIL TO REJECT the null hypothesis

--> We cannot "prove" the null hypothesis (always some non-zero chance we are incorrect)

13

## What is the Z-distribution?

###
-Just a special case of the normal distribution

-Idealized mean of 0 and S.D. of 1

-Allows us to use a corresponding z-table to look up critical values

14

## What are the Common Critical Z-scores?

###
1.65 = 90% CL

1.97 = 95% CL

2.58 = 99% CL

15

## In what situations do you use Single Sample Hypothesis Testing?

###
Situations where:

-There is a single sample and population

-Level of measurement of DV is interval-ratio

-There are known population values (u and o) of the variable to which we compare the man of the sample

--> Rare but not unheard of (ACT or IQ scores, census data, etc.)

16

## What is the critical region?

### It consists of areas under the sampling distribution (assuming null is true) that include unlikely sample outcomes.

17

## What value establishes the critical region?

### Z

18

## What is the size of the critical region reported as?

### Alpha - the most common alpha level is 0.05

19

## What does computing the sample Z statistic tell us?

### What are the odds of obtaining a difference in means this big if in fact there was no difference

20

## What is solving the equation for Z score equivalents called?

### Computing the test statistic (a.k.a. "Z (obtained)")

21

## When is H0 rejected?

###
If the test statistic falls in the critical region

-Reject H0 = support research hypothesis

22

## What if the test statistic does not fall in the critical region?

###
We fail to reject H0.

We don't "accept" or "prove" H0.

23