Please enable JavaScript.
Coggle requires JavaScript to display documents.
T-Statistics (Estimated Standard Error- estimate of the real standard…
T-Statistics
-
-
-
-
-
Formula for T Statistic is used to test the hypotheses about an unknown population mean, u, when value is unknown.
Degrees of freedom (df) df=n-1 describes the number of scores in a sample that are independent and free to vary.
-
- Must consist of independent observation
- Population sampled must be normal.
Due to Estimated Standard Error located in the denominator of a t-statistic a larger value for Estimated Standard Error produces a smaller value (closer to zero)
High variance reduces the likelihood of rejecting the null hypothesis. The larger the sample size the smaller the error.
-
Names the value after one of the statisticians who first substituted sample statistics into Cohen's formula.
-
A measure of effect size that determines what portion of the variability in the scores can be accounted for by treatment effect.
-
-
-
Cohens are not influenced at all by sample size and measures of r2 are only slightly affected by changes in the sample size (n)
-
-
Correlations
-
The Direction of the Relationship The sign of the correlation, positive or negative, describes the direction of the relationship.
-
-
Pearson correlation- measures the degree and the direction of the linear relationship between two variables.
r= the degree to which X and Y vary together divided by the degree to which X and Y vary separately.
-
Positive Correlation- the two variables tend to change in the same direction: as the value of the X variable increases from one individual to another, the Y variable also tends to increase; when the X variable decreases, the Y variable also decreases.
Ex. 
Negative Correlation- the two variables tend to go in opposite directions. As the X variable increases, the Y variable decreases. That is, it is an inverse relationship.
Ex:
-
-
-
-
-
Spearman Correlation- A correlation calculated for ordinal data. Also used to measure the consistency of direction for a relationship.
Spearman correlation is used to measure the relationship between X and Y when both variables are measured on ordinal scales
Definitional Formula for the sum of products is where Mx is the mean for x scores and My is the mean for y scores.
Sum of products of deviation- A measure of the degree of covariability between two variables; the degree to which they vary together.
-
-
-
-
-
Correlation is a statistical technique that is used to measure and describe the relationship between two variables.