psych 230 final

Authority

Accepting some thing as true because someone in a position of authority says so

Rationalism

Using logic and reasoning to arrive acknowledge

Intuition

Relying on a sudden insight or gut feeling that arises without conscious reasoning

Scientific method

Using empirical, systematic observation and experimentation to test hypothesis objectively

Observational studies

No variables are manipulated and researchers, simply observe and record behavior. Cannot determine causality. Includes naturalistic, observation, Parameter estimation And correlational studies

Experimental research

Researchers manipulate an independent variable to observe its a fact on a dependent variable, and it can determine causality

Descriptive statistics

Techniques used to summarize or describe characteristics of a data set for example the mean and range

Inferential statistics

Techniques that use sample data to make inferences or generalizations about a population

Independent variable

The variable manipulated by the experimenter

Dependent variable

The variable measured to assess the effect of the independent variable

statistic

A number that describes a characteristic of a sample, for example, sample mean

Parameter

A number that describes a characteristic of a population, for example, population mean

Nominal

Categories only for example, gender and brand

Ordinal

Categories with rank order, for example, race placement

Interval

Equal intervals, but no true zero for example temperature in Celsius

Ratio

Equal intervals and a true zero, for example, height and weight

Continuous variables

Infinite values between any two points, for example time and weight

discrete variables

Fixed countable values

Frequency distribution

Shows scores and how often they occur useful for organizing individualizing data

Ungrouped distributions

List individual scores

Grouped distributions

Combined scores into intervals for clarity when there are many data points

relative frequency

Proportion of scores in each interval

Cumulative frequency

Total scores up to a certain point

Cumulative percentage

Cumulative frequency as a percentage

percentile point

Score below which specific percentage of scores fall

Percentile rank

Percentage of scores below a specific score

Central tendency

Describes the center of a distribution (Mean, median and mode)

Variability

Describes the spread (Range variance and standard deviation)

Median

Middle school

Range

Difference between highest and lowest scores

Standard deviation

Average spread around the mean sample standard deviation uses and minus one and minus one to correct bias in the estimating population standard deviation

Variance

Square of the standard deviation

Which one of these is the effect of a symmetrical distribution?

Mean = median = mode

Which of these is the effect of a positive skew?

Mean >Median >mode

Which of these is an effect of a negative skew?

Mean<median<mode

Z score

Describes how far a raw score is from the mean in standard deviation units

Pearson r

For linear, continuous data

Spearman rho

For ranked/ordinal data

Why did the assumptions for Pearson r?

Linearity, Normality, Homoscedasticity

Regression

Predicting one variable from another

Regression line

Best fit line

Least squares criterion

Minimizes the sum of squared prediction errors

Standard error of estimate. Sy/x

Average distance from the regression line

Homoscedasticity

Equal spread of errors across values of X

Random sample

Each member has eagle chance of selection and it ensures Generalizability

Sampling with replacement

Selected units are returned to the population

Sampling without replacement

Selected units are not returned

Repeated measures design

Same participants in all conditions

Null hypothesis

No effect or difference

Alternative hypothesis

There is an effect or difference

Alpha level

Probability threshold, which is commonly .05 for rejecting the null hypothesis

practical importance

Real world relevance, regardless of statistical result

When do we use a one tailed test?

Use a one tail test if the alternative hypothesis predicts the direction

When do we use a two tailed test?

Use a detailed test of the alternative hypothesis does not predict direction

Type one error

Rejecting the null hypothesis when it’s actually true

Type two error

Retaining the null hypothesis when it’s actually false

What does the alpha level control?

The probability of a type one error

T test

Population standard deviation unknown, and uses sample standard deviation

Z test

Population standard deviation known

F distribution with anova

Used to compare more than two means

H0 with anova

All group means are equal

H1

At least one mean differs

MS between(numerator)

Variability due to treatment or group differences

MS within (denominator)

Variability within groups due to random error

Etta squared and omega squared measure______

Proportion of variance, explained

Omega squared adjusts for___

Bias

Eta squared may ____

Overestimate effect

Planned comparisons

Chosen before the experiment and are more powerful

Post hoc comparisons

Conducted afterANOVA Indicate significance; More conservative