PSYCH STATS REVIEWER

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Questions and Answers

What is the primary goal of inferential statistics?

To conduct experiments on a sample

To collect data from an entire population

To summarize and organize data

To make generalizations about a population from a sample (correct)

What type of variable has different values for different individuals, such as height or age?

Quantitative variable (correct)

Qualitative variable

Nominal variable

Ordinal variable

What is the term for a small group of individuals selected from a population?

Variable

Sample (correct)

Statistic

Population

What is the level of measurement that has no order or numeric value?

Nominal Signup and view all the answers

What type of sampling involves the random selection of research participants?

Probability sampling Signup and view all the answers

What is the term for the entire group of individuals that the researcher wants to study?

Population Signup and view all the answers

What type of variable can take on an uncountable set of values?

Continuous variable Signup and view all the answers

What is the term for statistical procedures used to summarize, organize, and simplify data?

Descriptive statistics Signup and view all the answers

What is the main characteristic of non-probability sampling?

It selects research participants because of convenience or access. Signup and view all the answers

What is the purpose of a frequency distribution?

To make the pattern of the data easier to see. Signup and view all the answers

What is the formula to calculate the class size?

Upper limit - Lower limit Signup and view all the answers

What is the most commonly used measure of central tendency?

Mean Signup and view all the answers

What is the characteristic of a skewed distribution?

The mean, median, and mode are in different positions. Signup and view all the answers

What is the formula to calculate the range?

Xmax - Xmin Signup and view all the answers

What does the standard deviation measure?

The average distance from the mean. Signup and view all the answers

What is the purpose of a z-score?

To specify the distance from the mean. Signup and view all the answers

What is the purpose of the Levene's Statistic in a One Way ANOVA?

To test for homogeneity of variances Signup and view all the answers

What is the term for the variable that distinguishes the groups in a One Way ANOVA?

Factor Signup and view all the answers

What type of test is used to compare the means of two or more groups?

One Way ANOVA Signup and view all the answers

What is the term for the strength of a linear association between two variables?

Magnitude Signup and view all the answers

What is the purpose of a post-hoc test in a One Way ANOVA?

To identify exactly the comparisons that have significant differences Signup and view all the answers

What is the graphical representation of a correlation coefficient?

Scatter plot Signup and view all the answers

What is the term for the measure of the degree of relationship between two variables?

Correlation coefficient Signup and view all the answers

What is the characteristic of a negative relationship in a correlation analysis?

Increase in one variable is a decrease in the other variable Signup and view all the answers

What is the purpose of setting the alpha level in a hypothesis test?

To define the concept of 'very unlikely' in a hypothesis test Signup and view all the answers

What is the null hypothesis in a hypothesis test?

There is no change, no difference, or there is no relationship Signup and view all the answers

What is the critical region in a hypothesis test?

The region where the null hypothesis is rejected Signup and view all the answers

What is the purpose of a directional hypothesis test?

To make a specific prediction about the direction of the treatment Signup and view all the answers

What is the assumption for using a T-test?

The population mean is known, but the population standard deviation is not known Signup and view all the answers

What is the purpose of a T-test for independent means?

To compare two distinct groups Signup and view all the answers

When is the null hypothesis rejected in a hypothesis test?

When the sample statistic is located in the critical region Signup and view all the answers

What is the purpose of a non-directional hypothesis test?

To determine if the treatment increases or decreases the target behavior Signup and view all the answers

Study Notes

Branches of Statistics

Statistics is a branch of mathematics that involves data collection, analysis, and presentation.
It has two main branches: Descriptive Statistics and Inferential Statistics.

Key Concepts

Population: the entire group of individuals that a researcher wants to study.
Sample: a small group of individuals selected from a population, usually to describe the population.
Variable: a characteristic or condition that is not constant and can change or have different values for different individuals.

Types of Variables

Quantitative Variable: a variable where the data represent amounts.
Discrete Variable: a type of quantitative variable that can be counted in a finite amount of time.
Continuous Variable: a type of quantitative variable that can take an uncountable set of values.

Levels of Measurement

Nominal Level: a level of measurement with no order or numeric value (e.g., gender, race, eye color).
Ordinal Level: a level of measurement with order, but no numeric value (e.g., ranking).
Interval Level: a level of measurement with ordered numbers that have meaningful divisions, but no absolute zero.
Ratio Level: a level of measurement with an absolute zero and all characteristics of an interval scale.

Descriptive Statistics

Frequency Distributions: a way of presenting data to make patterns easier to see.
Class Interval, Class Limit, Class Frequency, Class Size, and Class Mark: components of a frequency distribution.

Measures of Central Tendency

Mean: the most commonly used measure of central tendency.
Median: used when the mean might not be representative of a distribution.
Mode: the score in a distribution that occurs with the greatest frequency.

Measures of Variability

Range: the distance covered by the scores in a distribution.
Standard Deviation: a measure of the standard, or average, distance from the mean.
Variance: the average distance from the mean.

Hypothesis Testing

Null Hypothesis (Ho): there is no change, no difference, or no relationship.
Alternative Hypothesis (Ha): there is a change, a difference, or a relationship.
Alpha Level (level of significance): a probability value used to define the concept of "very unlikely" in a hypothesis test.
Critical Region: composed of extreme sample values that are very unlikely to be obtained if the null hypothesis is true.
Directional Hypothesis Test (one-tailed): a test that makes a specific prediction about the direction of the treatment.
Non-Directional Hypothesis Test (two-tailed): a standard hypothesis testing procedure.

T-Statistics

T-Test: used to test hypotheses about an unknown population.
Assumptions: population mean is known, but the population standard deviation(s) is not known; sample size is less than 30.
Types of T-Tests:
- Independent Samples T-Test (two-sample): two distinct groups are being measured.
- One-Sample T-Test: compares a sample mean to a population mean.
- Paired T-Test (dependent means): same group measured twice.

Analysis of Variance (ANOVA)

One-Way ANOVA: compares the differences in the means of two or more groups.
Factor: the variable that distinguishes the groups.
Levels of Factor: individual conditions or values that define the factor.
Levene's Statistic: assumes equal variances or not.
Post-hoc test: identifies exactly the comparisons that have significant differences.

Correlation

Correlation Coefficient: measures the degree of relationship between two variables.
Magnitude: strength of the relationship, determined by the correlation coefficient.
Scatter Plot (Scattergram): graphically represents a correlation coefficient.
Positive Relationship: an increase in one variable is related to an increase in the other.
Negative Relationship: an increase in one variable is related to a decrease in the other.

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