Research - Stats

median

good for when there are high and/or low outliers because it does not skew data

mode

value that appears the most in a data set

mean

the average of a data set

ordinal

level of measurement

• Clear rank/order

• categories

nominal

level of measurement

• No clear rank/order

• categories

• The least precise

interval

level of measurement

• No true zero

• Distance between variables matters

• data can be ordered and categorized

ratio

level of measurement

• Has absolute zero

• Can be added/subtracted/multiplied/divided

• The most precise

experimental

Type of study that examines cause and effect relationships

closest to 1

most desirable measure of reliability is a Pearson’s r that is…

scatterplot

best way to display relationship between 2 continuous variables

type 1 error

Type of error

• Rejects true null hypothesis

• false positive

interval

parametric statistics require measurements to be on the ___ scale

type 2 error

type of error

• failure to reject a null hypothesis

• false negative

validity

The extent to which a tool measures the data accurately

reliability

The extent to which a tool can be used again and again and have the same results

descriptive statistics

Type of statistics

• used to summarize and organize data

inferential statistics

Type of statistics

• used to make inferences about a population based on a sample

-1-+1

Range for Person’s correlation coefficient

direct correlation

Two variable that increase/decrease as the other one does (direct or indirect)

indirect correlation

Two variable that move in opposite direction (direct or indirect)

negative correlation

Both variables move down/decrease

positive correlation

Both variables move up/increase

Pearson’s R

Measures the strength and direction of the linear relationship between two continuous variables, ranging from

• -1 (perfect negative) to +1 (perfect positive)

• With 0 indicating no linear relationship.

alternative hypothesis

States there is a relationship between variables

null hypothesis

States there is not a relationship between variables

Parametric statistics

Inferential methods that assume sample data comes from a population with a known, specific distribution (usually normal) and defined parameters (mean, variance)

• used on continuous (interval/ratio) data to compare group means or assess relationships

small

what size sample would you want to use nonparametric statistics for?

nonparametric statistics

"distribution-free" methods used to analyze data that do not fit normal distribution assumptions, relying on data ranks or signs rather than raw values. These tests are ideal for small samples, ordinal data, or skewed data with outliers.

<.05

what is the most common value used to set the alpha that indicates statistical significance (P value)

t test

Statistical test that is used to compare two groups

ANOVA

Statistical test that compares mean values between three or more groups (f test)

Analysis of variance

p value

measures the probability that observed data occurred by chance, assuming the null hypothesis is true

alpha

pre-set, maximum acceptable risk of a false positive (type I error)

quasia-experimental

Type of study

• does not use random assignment

• establishes cause and effect

measure of central tendency

identifies a single value as the representative center of a data distribution ie mean, median, mode

convenience sampling

Type of sampling:

• researcher chooses a sample that is readily available in a non-random way

voluntary sampling

Type of sampling:

• researcher puts out a request for members of a population to join the sample

simple random

Type of sampling:

• every member and set of members has an equal chance of being included in the sample

stratified random

type of sampling:

• population is split into groups. The overall sample consists of some members from every group and the members from each group are chosen randomly

cluster random

Type of sampling:

• population is split into groups. Overall sample consists of every member from some of the groups, groups are selected at random

systemic random

Type of sampling:

• members of the population are put in some order. A starting point is selected at random and every nth member is selected to be in the sample