Correlation Coefficient

statistic that indicates the strength and direction of the relationship between two variables for one group of participants

?

can range from -1 (perfect inverse relationship) to 1.00 (perfect, direct, relationship)

 0.00 indicates no relationship

What are the ranges and values that a correlation coefficient can be?

Pearson r and Spearman's rho

What are two very frequently used correlation coefficients?

relationship btw two scale variables

dist. of scores is symmetrical/not skewed

reltationship is not curvilinear

When to use the Pearson r?

when either of these conditions are met:

1. one or both of the variables are ordinal

           2. One or both of the distributions are clearly not symmetrical (highly skewed)

When do you use the Spearman's rho?

1. Analyze

 2. Correlate

3. Bivariate

         4. Click Spearman

4 steps in SPSS to calculate the Pearson r and Spearman's rho?

weak

Correlation coeffcients:

values between .01 - .24?

Moderate

Correlation coefficients:

values between .25 - .49?

moderately strong

Correlation coefficients:

values between .50 - .74?

very strong

Correlation Coefficients:

values between .75 - .99?

Perfect

Correlation Coefficients:

values of 1.00?

r

round to two decimal places

What is the symbol and rounding rule for Correlation Coefficients?

to determine whether the mean for a random sample of participants differs significantly from a known value or hypothetical value

What is the purpose of a t Test for a Single Sample Mean?

when the mean for one set of scores is to be compared with a known or hypothetical mean

only for interval and ratio (scale) distributions that are not highly skewed

When should a t test for the sample mean be used?

1. analyze

2. compare means

3. one sample t test

4. move variables over with arrow

5. put the known mean/avg in the Test Value box

6. click OK

Steps in SPSS to conduct a one sample mean t test?

difference is statiscially significant at the .001 level

Rule for probability if it is equal or less than .001?

difference is statistically significant at the .01 level

Rule if probability is equal or less than .01?

difference is statistically significant at the .05 level

Rule if probability is equal or less than .05 but greater than .01?

difference is not statistically significant at the .05 level

Rule for probablility if it is greater than .05?

probablilty is greater than .05

if the difference is not statistically significant

One sample t test -

when do you accept the Null?

When the probability is less than .05 and the difference is statistically significant

One sample mean t test -

When you reject the null?

when each score underlying one  mean has been paired with a score underlying the other mean

When is a paired - sample t test appropriate?

1. analyze

2. compare means

3. paired samples t - test

4. move variables over

Steps in SPSS for a paired sample t- test?

using an experimental and a control group

Example of a independent samples t - test?

1 = experimental group

2 = control group

Lables in SPSS for independent sample t - test?

1. analyze

2. compare means

3. indpndnt sample t test

4. click bottom arrow to move exp n control to the grouping variables box

5. click on define groups

6. type 1 for group 1 and 2 for group 2

7. move variable into the test variables box

Steps in SPSS for conducting independent sample t-test?

use the figures in the top row if the value of Sig is greater than .05, so report that t and df

use values in the second row if the value of Sig is less than .05

How to analyze the sig for the Levense Test for Equality of Variances?

determine the significance of the difference between two or more means

What is a one way ANOVA used for?

The null hypothesis is rejected

If the difference is statistically significant...?

1. analyze

2. compare means

3. one way anova

4. move factor into the factor box

5. move dependent variable to the other box

6. click options, check descriptives

Steps in SPSS for a one way ANOVA?

Nominal data

What type of data is used for a chi squared goodness of fit test?

1. analyze

2. nonparametric test

3. chi-squared

4. move variable over

Steps in SPSS for chi squared goodness of fit test?

x²

Symbol for chi-squared?

used to test the statistical significance of the relationship between two nominal variables

What is the chi-squared test of independence used for?

1. analyze

2. Crosstabs

3. move variables to columns/rows

4. click statistics

5. check Chi-squared

Steps in SPSS for Chi-squared test of indpendence?

consists of words,names, (not numbers) that put research participants into distinct categories

Define:

Nominal Data

?

puts participants in order from high to low, can be obtained by ranking

ex) college degrees

Define:

ordinal data

?

each score point is  equally distant from each other score point ; doesnt have an absolute zero

ex) Likert Scales

SAT scores

Define:

Interval Level Data

?

each score point is equally distant from each other score point and has an absolute zero

ex) weight

Define:

Ration Level Data

?

Categorical data

Nominal and Ordinal data

aka?

Scale data

Ratio and Interval data

aka?

Frequency distribution

statistical table that lists the scores in one column and shows the number of participants who earned each score in the next column?

N

symbol for number of cases in the population?

n

Symbol for number of cases in the sample?

Publication Manual for the American Psychological Association

Type of format used for reporting in research reports?

Histogram

statistical figure that consists of vertical bars, the heights of the bars are proportional to frequencies?

Scale

Histograms should be created for ______ variables?

Categorical variables

Bar charts should be created for _____ variables?

Normal Curve

One of the most important characteristics of a histogram is whether it approximates the _______?

Frequency polygon

Line drawing that shows the frequency for each score in a distribution?

Statistical figure

Drawing that represents statistical output?

Statistical table

ordered set of statistical values without drawings?

mean

Balancing point in a distribution of scores?

median

middle point in a distribution of scores?

mean

most frequenctly used measure of central tendency published in research?

mode

most frequently occuring score in a distribution?

distribution is highly skewed

scores are at the ordinal level of measurement

conditions to be met for using the median?

distribution is not highly skewed

scores are at the scale level

Conditions to be met to use the mean to describe a distribution?

Median

What average do you use for highly skewed data?

mean

What average do you use for a distribution that is not highly skewed?

Report them at 2 more places than the original data

ex) 2 --> 2.00

Rule of thumb about reporting statistics for decimal places?

standard deviation

The number of score points out from the mean of a normal distribution that includes 34% of the cases?

variability

Standard deviation is a measure of ______?

interquartile range

Appropriate measure of variability when the median is selected as the measure of central tendency?

input variable/stimulus variable

Other names for Independent variable?

outcome variable/ response variable

Other names for the Dependent variable?

z-score

The expressed standard deviation in units?

-3 to 3

The typical range of z-scores?

individual has the same score as the average particiapant in a group

What does a z-score of 0.00 mean?

person has the same score as a participant who is one standard deviation above the mean

What does a z-score of 1.00 mean?

same score as a participant who is two standard deviations below the mean

What does a z-score of -2.00 indicate?

the partiticpant is above average

A positive z-score indicates that....?

the participant is below average

What does a negative z-score indicate?

1. analyze

2. descriptive statistics

3. move variables over

4. click on Save Standardized values as a variable

Steps in SPSS to find the z-scores?

scattergram

statistical figure that displays the relationship between to scale variables?

correlation coefficient

A scattergram should be examined before calculation the _____ _____?

the x - axis

In a scattergram, the predictor variable should be put on the ____ ?

the y - axis

In a scattergram, the variable being predicted should be placed on the ____?

on either axis

If prediction is not involved, it is okay to put the variables ____ on a scattergram?

Strong inverse linear relationship

strong direct linear relationship

  [image]

curvilinear

Relationship that is neither direct nor inverse?

correlation statistics

___ ____ are not appropriate for describing a curvilinear relationship?