Descriptive Statistics
Define mean, median, and mode.
Mean - the average
Median - the middle value
Mode - the most frequent value
Define standardized scale.
a characteristic of interval and ratio level of measurement where there are equal distances between each possible data point
A correlation examines a _________ between two groups.
relationship
What is the purpose of t-tests?
To analyze differences between groups.
Null - the assumption of no differences between groups.
Alternative - the assumption of differences between two groups.
True or False: A z distribution always sets the mean to 0 and standard deviation to 1.
True
What are the four levels of measurement?
nominal, ordinal, interval, ratio
What do we look at for the direction of a correlation?
The sign (+/-) of the correlation coefficient.
What is the difference between Independent Groups and Repeated Measures tests?
Independent Groups - multiple groups tested once
Repeated Measures - one group tested multiple times
Define p.
significance level; the measured probability of error in your analysis
Identify and define the 4 characteristics of a normal distribution.
1. symmetric - the same on both sides
2. asymptotic - the lines continue forever, never crossing zero
3. area under curve can be represented as probability
4. area under curve always equals 1
What are the four characteristics that determine level of measurement?
mutually exclusive, order to scale, standardized scale, meaningful zero
How do we determine the strength of a correlation?
The absolute value of the correlation coefficient.
Provide two differences between parametric tests and non-parametric tests?
- level of measurement of DV
- type of IV
- sample size
Define alpha.
error rate; the probability the researcher is willing to accept that the conclusion they draw from their analysis is wrong
A distribution with a mean and median to the left of the mode is skewed in what direction?
Negative
What level of measurement is temperature (*F)? Why?
Interval - mutually exclusive, order to scale, standardized scale, but no meaningful zero
Provide an alternative hypothesis for a research example analyzing the relationship between study time and exam grade in RSCH 610.
The greater the time spent on studying, the higher the exam score in RSCH 610.
Describe homogeneity of variance and how it is interpreted.
Homogeneity of variance = a comparison of the differences within groups.
Interpreted the opposite of t-test. We want groups to be similar therefore we want p > .05.
Define Type I error.
rejecting the null hypothesis when the null is true
List 5 characteristics of a good graph.
- show the data
- get the reader thinking about the data
- avoid distorting data
- present many numbers with minimum ink
- make large data sets coherent
- reveal trends
Why is level of measurement important in research?
- determines how data is organized
- determines how data can be reported
- determines what statistics can be conducted
What values outline a weak, moderate, and strong relationship?
Weak = 0 to .3
Moderate = .3 to .6
Strong = .6 to 1
What statistical language is present in a Mann Whitney U null hypothesis?
no "mean rank" differences between groups
Ex: No mean rank differences are expected in the sport satisfaction of basketball and soccer players.
Define Type 2 error.
accepting the null when the null is false