Week 5 Flashcards
What is the frequency of distribution?
It indicates the no. of individuals who receive each possible score on a variable. It is visually demonstrated through pie graphs, bar graphs, frequency polygons (line to represent distribution of frequencies of score), histogram (shows frequency through bars).
What is central tendency?
What the sample as a whole, or on the average is like.
What is the mean?
Set of scores obtained by adding all the scores and dividing by the number of scores (M)
What is the median?
Score that divides the group in half.
What is the mode?
Most frequent score.
What is standard deviation?
Average deviation of scores from the mean. Calculated by first calculating the variance. The standard deviation is small when most people have scores close to the mean.
What is the range?
Highest and lowest scores.
What axis does the independent variable go on?
x-axis
What axis does the dependent variable go on?
Y-axis
What is a correlation coefficient?
How strongly variables are related to each other.
What is pearson product-moment correlation?
Provides strength of relationship and direction of relationship (r). Only detects linear relationships and will not detect curvilinear relationships
What are scatterplots?
Each pair of scores plotted as a single point in a diagram.
What is the effect size?
The strength of association between variables.
What correlations are small, medium and large?
.15 (.10 to .20) are small
.30 are medium
.40 are large
What is r squared?
r squared is the squared value of a correlation coefficient and allows r to be presented as a percentage. r squared is referred to as the per cent of shared variance between two variables.
What are regression equations?
Regression equations are calculations used to predict a person’s score on one variable when that persons score on another variable is already known.
Y = a + bX
Y - score wished to be predicted
a - a constant
b - weighting adjustment factor
X - score we know
What is multiple correlation?
Multiple correlation (R) is used to combine a number of predictor variables to increase accuracy of prediction of a given criterion or outcome variable.
What is the third-variable problem?
An uncontrolled third variable may be responsible for the relationship between the two variables.
What is a partial correlation?
A correlation between two variables of interest with the influence of the third variable removed from or partialled out of the original correlation.
What is Chi-squared?
x squared - used with nominal scale data. Examines extent to which the frequencies that are actually observed differ from the frequencies that are expected if the null hypothesis is correct.
The significance of x squared can be evaluated by consulting a table of critical values of x squared. The critical values indicate the value that the obtained x squared must equal or exceed to be significant at the .10 level, the .05 level and the .01 level.
