PSY 230 Final Exam

If the power of an experiment is .7, the probability of making a Type II error is ______.

.3

The sum of all the individual deviation scores will always equal ____.

0

Power can vary from:

0 to 1

Beta equals: (equation)

1 - power

If you retain the null hypothesis, you may be making (two options):

1. A correct decision 2. Type II error

A bar chart should NOT be used for (3):

1. Continuous variables 2. Ratio level variables 3. Interval scales of measurement

Use a bar graph with data of what kind of measurement scales? (2)

1. Nominal (categories) 2. Ordinal (rank orderings rather than raw scores)

The analytic technique that is best for assessing the effects of two independent variables on a dependent variable is known as:

2-way ANOVA

What type of ANOVA is required to analyze the following data: There are 2 factors, 1. Caffeine intake before the exam (0 mg, 200 mg, or 400 mg) 2. Hours of sleep the night before the exam (0-3 hours, 4-6 hours, or 6+ hours)

3x3 factorial ANOVA: two factors, both of which have 3 levels

If SS total = 20 and SS between = 14, SS within = ?

6

Pearson's r is:

A measure of the paired scores

The two-way ANOVA allows what?

An assessment of the interaction between two independent variables

The variability within groups (MS within) is assumed to be due to:

Chance

In a/an _______-groups design, you use the same raters, and in a/an ________-groups design, you use different raters

Correlated; independent

Descriptive statistics vs. Inferential statistics

Descriptive: describe or characterize data (central tendency, variability, shape, etc.) Inferential: use obtained sample data to make inferences and draw conclusions about the population (probability, t-tests, etc.)

If F obtained is less than 1, we:

Do not need to compare it to F critical (the treatment did not have a significant effect)

The null hypothesis for an F test states:

Each group is a random sample from populations where the group means are equal

Omega squared and eta squared are measures of:

Effects size

ANOVA is also known as a/an...

F test

The ________ increases with the effect of the independent variable

F value

True or False: larger samples will always have larger values of the range.

False

True or False: Spearman's rho is the slope of the least squares regression line when the scores are plotted as z scores

False; Pearson r

Fahrenheit or Celsius are measured on the ____ scale of measurement while Kelvin is measured on the ____ scale.

Interval; ratio

When the line is horizontal, there is or is not a main effect? When the line is NOT horizontal, there is or is not a main effect?

Is not Is

If the probability level of an experiment is less than or equal to the alpha level, you ____ the null hypothesis

Reject

If the z-obtained value is in the critical region, what is the appropriate conclusion for the test?

Reject null hypothesis

How is eta squared calculated?

SS between / SS total

When calculating F critical, the DF numerator is:

The DF between (k-1)

When calculating F critical, the DF denominator is:

The DF within (N-k)

The larger F obtained becomes, the more reasonable it is that:

The IV had a real effect

The main effect of factor A is defined as:

The effect of factor A averaged over all of the levels of factor B

"Jumping the gun" (Saying there is an effect when there really isn't) is an example of which error?

Type I error

If a researcher sets a conservative alpha of .001, they are likely concerned about which type of error?

Type I error

"Missing the boat" (Saying there is not an effect when there really is one) is an example of which error?

Type II error

If alpha is changed from .05 to .01, the probability of a Type ___ error increases

Type II error

To ethically increase the probability of rejecting Ho, you should:

Use the most powerful test

The advantage of a powerful experiment is that:

You are more likely to detect the real effects of the IV, if there are any

A type II error occurs when:

You incorrectly retain a false null hypothesis (false negative) Ex: Let a guilty person free in trial

The proportion of variance accounted for by a correlation between 2 variables is determined by ____.

r squared

In a normal distribution, what z-score value separates the lowest 50% of all the scores from the rest of the scores? (What is the mean?)

z = 0.00

Factors that affect power (4) and their relationship (inverse or direct)

1. Alpha level (direct relationship: increase alpha, increase power) 2. Sample size ( direct relationship: increase sample size, increase power) 3. Effect size (direct relationship: larger effect size will have greater power) 4. Sample variability (inverse: the greater the sample variability, the lower the power to detect a real effect)

Characteristics of a sampling distribution of a statistic (3):

1. Gives all the values a statistic can take 2. Gives the probability of getting each value of a statistic under the assumption it is due to chance alone 3. Is a probability distribution

Use a histogram with data of what kind of measurement scale? (2)

1. Interval (equal intervals between adjacent units, NO absolute zero point) 2. Ratio (equal intervals between adjacent units, there IS and absolute zero point)

As the difference between the group means increases, these increase as well (3 things)

1. MS between 2. Treatment effect 3. F obt

Conditions for a binomial distribution (5)

1. There is a series of N trials 2. On each trial, there are only 2 possible outcomes (dichotomous) 3. Outcomes are mutually exclusive 4. Trials are independent 5. The probability of each possible outcome on any trial stays the same for each trial

What is true about an a priori (planned) comparison? (3)

1. They have higher power than post hoc comparisons 2. Used only when there is adequate theoretical support 3. Use the same basic formula as the single-sample t test

Types of posteriori (post hoc) comparisons (2)

1. Tukey's HSD (Honestly Significant Differences) test: most common, controls for all pair-wise mean comparisons 2. Scheffe test: more conservative, controls for every comparison

When interpreting F(2,18), how many participants were involved?

21 F(DF between, DF within), DF within = N - k = 18, k = 3

The two-way ANOVA results in the calculation of ___ F ratios

3

When interpreting F(2,18), how many groups were examined?

3 F(DF between, DF within), DF between = k - 1 = 2

In a normal distribution, what percent of scores fall between a z-score of -1 and the mean?

34.13%

The more non-parallel the lines are in an interaction plot, the _______ the strength of the interaction.

Greater

After conducting a one-way ANOVA, you get a p value of .161. What does this mean in terms of HOV and significant difference?

HOV was not violated (p is greater than .05) There was no significant difference between the means of one or more groups tested (p is greater than .05)

A distribution is negatively skewed when most of the scores occur at the higher or lower end?

Higher

When analyzing the results of ANOVA tests, if your p value is less than or equal to .05, what is violated?

Homogeneity of Variance (HOV)

An alpha level of .05 indicates that:

If the null hypothesis is true, the probability of falsely rejecting it (making a Type I error) is limited to .05

Restricting the range of X or Y will increase or decrease the correlation?

Increase

Researchers want the statistical power of the test to be relatively high (at least .80) because this will:

Increase the probability that a false null hypothesis will be rejected

In ANOVA tests, the word "factor" denotes the:

Independent variable

When the effect of one factor is not the same at all levels of another factor, a/an _____________ is said to have occured

Interaction

When the lines are parallel in the interaction plot for a 2-way ANOVA, there is or is not an interaction?

Is not (if lines are not parallel, there is probably an interaction)

You're exploring the differences in exam scores (DV) associated with varying amounts of sleep (IV). You categorize the amount of sleep into groups: high, medium, and low. In terms of ANOVA, these groups are called:

Levels

The one-way ANOVA partitions total variability into two groups:

MS between and MS within (MS = variance estimate)

Maximizing power in an experiment ________ beta

Minimizes

What is the most desirable amount of power for an experiment? The most common?

Most desirable: .80 Most common: .40-.60

Why don't we use multiple t tests instead of ANOVA to compare group means?

Multiple t tests would increase (inflate) the probability of a Type I error

Spearman's rho should be used when examining the relationship between two variables when one or both are measured on the __________ scale

Ordinal

Using letter grades (A, B, C, D, F) to classify student performance on an exam is an example of measurement on a/an ______ scale of measurement

Ordinal

When analyzing the results of ANOVA tests, one or more group means are significantly different if:

P value is less than or equal to .05

In an experiment with 8 subjects involving a non-directional alternative hypothesis, the obtained results were 7 pluses and 1 minus. To evaluate the null hypothesis, what probabilities would you add together?

P(0) + P(1) + P(7) + P(8)

The reason we don't use multiple t-tests when comparing more than two groups is due to:

Preserving the alpha level

If F obtained is equal to or greater than F critical, we ________ the null hypothesis

Reject

An example of a test that is designed to compare all possible pairs of means while maintaining the Type I error is a:

Scheffe test

What constitutes a small effect size when calculating omega squared and eta squared? Medium? Large?

Small: .01-.05 Medium: .06-.13 Large: .14 and beyond

The closer the points on a scatter plot are to the regression line, the ____ the correlation is between the scores.

Stronger

The variability between groups (MS between) is assumed to be due to:

The effect of the independent variable

A main effect for variable A means that:

The effect of variable A is significant when averaged over all levels of variable B

A significant interaction effect indicates that:

The effects of one variable are NOT the same at all levels of the other factor

The two-way ANOVA assesses:

The effects of two independent variables in one experiment

The between groups estimate increases with the effect of:

The independent variable

The effect of one factor averaged over the effects of another factor is called:

The main effect

The larger F obtained becomes:

The more reasonable it is that the independent variable had a real effect

The Pearson r coefficient is used to determine what, and of what units?

The relationship between 2 variables which are measured on different units

In a repeated measures design experiment...

The same subjects receive both treatments

What does a 2x3 factorial ANOVA mean? Give an example

There are 2 factors (IVs), and the first factor has 2 levels and the second has 3 levels Ex: Factor 1: sex (male or female), Factor 2: Treatment (1, 2, or 3)

A type I error occurs when:

You incorrectly reject a true null hypothesis (false positive) Ex: convict an innocent person

When a variable is continuous, the probability of event A occuring equals:

the area under the curve corresponding to A divided by the total area under the curve

The null hypothesis in the one-way ANOVA asserts that:

μ1 = μ2 = μ3 = μN