Monday, February 26, 2018

Independent Samples t-test




Independent Samples t-test








Researchers use the independent samples t-test to find out if there is a significant difference between two sets of data. In the behavioral sciences, the data are often two sets of scores on tests or survey items.

Significance can mean a lot of different things. In behavioral science, it is common to think of significance as a frequently occurring, and thus reliable, difference. Sometimes the language of statistics can be confusing. The independent sample t-test evaluates the differences between the arithmetic means of the two groups of scores, and assumes the scores are normally distributed.

Usually, a difference needs to be at least large enough that a score difference as large, or larger than the one obtained, occurs only 5% of the time by chance.

The calculations are usually done in spreadsheets like Excel or Google Sheets or in a program like SPSS

You will find the following text in Chapter 16 of Creating Surveys. I also cover t-tests in Statistics for Counselors.





Creating Surveys

Create better surveys for work and school



DOWNLOAD today AMAZON




The statistical procedure results in a t-value and a p value. The larger the t-value, the more likely it is that the difference between the group means is significant. The p-value represents the probability that the t-value of the size obtained did not occur by chance. As in many cases, the p-value is reported based on a 95% probability that the t-value did not occur by chance. The p-value is usually reported by considering the likelihood that it occurs by chance greater or less than 5% of the time where 5% is written as .05. If the probability is less than .05 that a t-value as large or larger than the one obtained did not occur by chance, the researcher would report the results as p < .05. If the t-value was too small to meet the level needed for significance, the researcher would just report the finding as not significant (p > .05).

I and my colleagues have studied forgiveness. Suppose we found that people who attended a forgiveness seminar obtained higher forgiveness scores compared to those who did not attend.
Here’s how we might write the results (Chapter 16, Creating Surveys).

We found that people who did attended the forgiveness seminar were significantly more forgiving (M = 39, SD = 5) than were people who did not attend the seminar (M = 30, SD = 5), t (98) = 6.75, p < .05.




Applied Statistics: Concepts for Counselors


Available in over 12 countries.


You can calculate the independent samples t-test by hand. If you are interested, here's a link to an example at UC Davis. 

Also, here is an online calculator where you can enter two sets of values and obtain a t-test result.
EasyCalculation.com



Connections and Links to Resources

My Page    www.suttong.com

My Books   AMAZON

FACEBOOK   Geoff W. Sutton

TWITTER  @Geoff.W.Sutton

LinkedIN Geoffrey Sutton  PhD

Publications (many free downloads)
     
  Academia   Geoff W Sutton   (PhD)
    
  ResearchGate   Geoffrey W Sutton   (PhD)










Thursday, February 22, 2018

How to Quickly Score Negatively Worded Survey Items





You can quickly reverse score survey items using widely available spreadsheets like Excel and Google Sheets or SPSS.







For example, the freely available scale to measure Valor/ Bravery/ Courage has 10 items rated on a 1 – 5 scale. High scores represent more of the trait. But 4 items are worded as negative statements so, you have to reverse the item scores on the negative items to obtain a correct total score for courage.

Sometimes test and survey creators refer to items as + or – keyed. Positive items are added together and the negative items must be reverse scored before adding to the total.

Survey Items Example

Following are the general directions for the 5-point rating from www.ipip.org

Describe yourself as you generally are now, not as you wish to be in the future. Describe yourself as you honestly see yourself, in relation to other people you know of the same sex as you are, and roughly your same age. So that you can describe yourself in an honest manner, your responses will be kept in absolute confidence. Indicate for each statement whether it is 1. Very Inaccurate, 2. Moderately Inaccurate, 3. Neither Accurate Nor Inaccurate, 4. Moderately Accurate, or 5. Very Accurate as a description of you.

Here are two items from the "Courage" scale item list.

A positive or + keyed item
1. I have taken frequent stands in the face of strong opposition.

A negative or – keyed item
2. I do not stand up for my beliefs.

Scoring

Suppose a participant rated number 1 as “4” and number 2 as “4” You would need to reverse the score for item 2 before calculating a total.

A simple procedure is to subtract the obtained score from the highest possible item score plus 1. The highest possible score is 5 and 5 + 1 = 6. The reverse score of item 2 is therefore 6 – 4 = 2. So, on a 5-point rating scale where 5 is the high score you would reverse the scores for each negatively worded item individually or use the formula in a spread sheet where you can use the same reverse scoring formula for all negatively worded items.

Spreadsheets and Reverse Scoring

Here’s an example of a simple spread sheet for reverse scoring. The formula in column D for positive items is simply = B3 (or whatever column and row contains the original score) and for the negative items is simply 6 – C4 (or whatever column and row contains the original score for the negative items).

A
B
C
D
Item #
Positive Scores
Negative Scores
Final Item Scores
1
3
3
2
4
4
3
2
2
4
4
2
5
2
4
Total
15.00
Mean
3.00
SD
1.00




Creating Surveys

Create better surveys for work and school



DOWNLOAD today AMAZON





SPSS and Reverse Scoring

If you are using SPSS, you can use the Recode into Different Variables procedure on the Transform tab at the top of your spreadsheet.

NOTE: Enter all your data first, because SPSS does not update newly entered scores after you have performed the procedure.

The Recode box opens to show a list of your items such as Q1, Q2 etc.

Move the item to be recoded into the box at the right and enter a new name such as Q1rev etc.

Click Old and New Values

Enter the correct values according to your scale. For example, on a 5-point scale the reverse coding is:  1 = 5, 2 = 4, 3 = 3, 4 = 2, 5 = 1

Click Continue and OK. The new values will be listed under Q1rev etc.

Following is a link to a YouTube video showing how to reverse score in SPSS using the recode procedure.  https://www.youtube.com/watch?v=lrI_2N3LlQM 





Connections and Links to Resources

My Page    www.suttong.com

My Books   AMAZON

FACEBOOK   Geoff W. Sutton

TWITTER  @Geoff.W.Sutton

LinkedIN Geoffrey Sutton  PhD

Publications (many free downloads)
     
  Academia   Geoff W Sutton   (PhD)
    
  ResearchGate   Geoffrey W Sutton   (PhD)




Applied Statistics: Concepts for Counselors


Available in over 12 countries.





Wednesday, February 14, 2018

How to Measure Courage

Lions of Kruger/ Geoff Sutton 2009



Courage is a virtue.

Despite being an ancient virtue, courage is a relatively new topic of study in psychological science. As with any psychological concept, definitions can vary. Woodward and his colleagues have begun a line of inquiry, which includes a measurement scale.

Here’s a 2007 definition:

“Courage is the voluntary willingness to act, with or without varying levels of fear, in response to a threat to achieve an important, perhaps moral, outcome or goal. (p. 136)”

Factor analysis suggested participants identified three types of threats: Physical, social, and emotional. When scale items were analyzed, four factors emerged, which were categorized by the authors as follows:

1. work/employment courage
2. patriotic/religion/belief-based courage
3. social-moral courage
4. independent or family-based courage

23-item Measure

A popular measure of courage is the Woodard Pury Courage Scale, which consists of 23-items (2007).

Each item describes a situation. Participants read each item and provide two responses. First, they provide a rating of agreement from 1 = Strongly Disagree to 5 = Strongly Agree. Second, they rate how fearful they would be in a situation from 1 = Little Fear to 5 = Very High Fear.

Items deal with various life situations such as highly challenging work situations and intervening in a dangerous interpersonal situation.


Educators, researchers, and students may want to add a courage scale to their survey projects.



Creating Surveys

Create better surveys for work and school



DOWNLOAD today AMAZON





Conditions of Use

The scale may be used in non-commercial research and educational survey projects. Contact the author for commercial use. The full scale is protected by copyright and not for public posting.


Locating the full set of scale items

Find the scale in the article—see the reference at the end of this post. The 23-items are listed in the Appendix to the article (page 147). It is also available for download in PsycTESTS ®


Reference
Woodard, Cooper R., & Pury, Cynthia L. S. (2007). The construct of courage: Categorization and measurement. Consulting Psychology Journal: Practice and Research, 59(2), 135-147. doi: 10.1037/1065-9293.59.2.135




Connections and Links to Resources

My Page    www.suttong.com

My Books   AMAZON

FACEBOOK   Geoff W. Sutton

TWITTER  @Geoff.W.Sutton

LinkedIN Geoffrey Sutton  PhD

Publications (many free downloads)
     
  Academia   Geoff W Sutton   (PhD)
    
  ResearchGate   Geoffrey W Sutton   (PhD)







Sunday, February 11, 2018

How to measure love



Can you measure love? Robert Sternberg thinks so.


Early clinical perspectives on love can be found in the works of Freud and Maslow. But scientific approaches have looked at the many dimensions of love in the last few decades.

One popular theory is the Triangular Theory of Love presented by Robert J. Sternberg. As the name implies, there are three constructs in this theory of interpersonal love: Intimacy, passion, and commitment/decision (see Sternberg, 1986, for an explanation). Sternberg referred to each with a "temperature" rating from hot to cool--see the parentheses below.


Intimacy refers to lovers’ emotional investment in their relationship (feeling close, connected, bonded, a measure of "warmth").

Passion refers to lovers’ motivational involvement in their relationship (romance, attraction, sex, a measure of "hot").

Commitment/decision refer to lovers’ thoughts about their relationship in terms of decision (I love…) and commitment to the long-term relationship (a measure of "cool").

STERNBERG’S TRIANGULAR LOVE SCALE (TLS or STLS)

The scale has 45-items, which are rated on a 9-point scale. The end points are 1 = Not at all and 9 = Extremely. The midpoint label of 5 = Moderately. The other numbers do not have text labels. Each of the three dimensions (intimacy, passion, commitment/decision) include 15 items.

Following are examples (I will post a link to the full scale below).

Intimacy
______ 1. I am actively supportive of ____________’s well-being.
______ 2. I have a warm relationship with ____________.

Passion
______ 18. My relationship with ____________ is very romantic.
______ 19. I find ____________ to be very personally attractive.

Commitment/decision

______ 31. I know that I care about ____________.
______ 32. I am committed to maintaining my relationship with ____________.

Educators, researchers, and students may want to add a love scale to their survey projects.



Creating Surveys

Create better surveys for work and school



DOWNLOAD today AMAZON





Reliability and Validity

The values reported in the 1997 article indicate high reliability values in the .80s and .90s. Factor analyses supported the three-part theory. Validity values were also favorable. For example, Sternberg compared his scale to the Rubin Scales.

Links to the full scale (I do not gaurantee these external links work). If they do not work, try using a search engine to find the Sternberg Triangular Theory of Love scale.




 Clinicians may want to use some or all of the items in their counseling practice.



Applied Statistics: Concepts for Counselors


Available in over 12 countries.


References

Sternberg, R. J. (1986). A triangular theory of love. Psychological Review, 93, 119-135.
Sternberg, R. J. (1997). Construct validation of a triangular love scale. European Journal of Social Psychology, 27, 313-335.





Connections and Links to Resources

My Page    www.suttong.com

My Books   AMAZON

FACEBOOK   Geoff W. Sutton

TWITTER  @Geoff.W.Sutton

LinkedIN Geoffrey Sutton  PhD

Publications (many free downloads)
     
  Academia   Geoff W Sutton   (PhD)
    
  ResearchGate   Geoffrey W Sutton   (PhD)







Friday, February 9, 2018

Feeling Competent to Parent





Parents sometimes feel inadequate to parent. Although many enjoy parenting and delight in their children, few can deny that parenting is often a challenge. Some feel unprepared. Some enjoy their children but feel frustrated. Some feel they are less capable than other parents.

The Parenting Sense of Competence scale (PSOC) consists of 17 or 16 items depending on the version. The items are rated on a scale of 1 to 6 with anchors of 1 = strongly disagree to 6 = strongly agree.

Authors: Gibaud-Wallston & Wandersman (1978)

Internal consistency estimates of reliability range from the mid .70s to .80s in previous studies.
Research suggests that the items can be grouped into two subscales: Satisfaction with Parenting and Efficacy.


Early wording of some scale items used only the word “mother,” but these items have been revised by other researchers to refer to either mother or father (e.g., see Ohan, Leung, & Johnston, 2000).

Scoring: Several items are reverse-scored. See below for the download links to the PSOC scale with scoring instructions.

Although, the PSOC has been reported in research studies, clinicians may consider the scale useful in work with clients. Average scores for mothers and fathers of children in different age groups can be found in the Ohan et al. (2000) study. Clearly, samples may differ therefore, clinicians must be careful to note that score differences they obtain may be due to different samples rather than different levels of sense of competence in parenting. Clinicians are advised to develop local norms for all scales.

Also relevant to readers unfamiliar with research-- the PSOC scale measures a parent's sense of competence -- the scale does not measure actual competence. Thus, a parent may feel low on competence but actually be highly competent within one's culture.




Applied Statistics: Concepts for Counselors


Available in over 12 countries.



Examples of instructions and two items are as follows:

Please rate the extent to which you agree or disagree with each of the following statements.

Strongly                                           Somewhat          Somewhat                                          Strongly
Disagree              Disagree              Disagree              Agree                    Agree                    Agree
      1                             2                             3                       4                             5                             6


8.   A difficult problem in being a parent is not knowing whether you’re
      doing a good job or a bad one.                                                                                         


15.  I honestly believe I have all the skills necessary to be a good mother
       to my child.                                                                                                                            


In their survey, Ohan and her colleagues included the Child Behavior Checklist and the Child-Rearing Practices Report (see reference and article link below).




Creating Surveys

Create better surveys for work and school



DOWNLOAD today AMAZON




DOWNLOAD: The Ohan et al. (2002) article, which includes the scale is at this link:



REFERENCES

Gibaud-Wallston, J., & Wandersman,  L.P. (1978, August). Development and utility of the Parenting Sense of Competence Scale. Paper presented at the meeting of the American Psychological Association, Toronto, Canada

Ohan, J., Leung, D.W., & Johnson, C. (2000). The parenting sense of competence scale: Evidence of a stable factor structure and validity. Canadian Journal of Behavioural Science, 32, 251-261. Doi 10.1037/h0087122



DISCIPLINE WITH RESPECT is an evidence-based parenting approach.





















Connections and Links to Resources

My Page    www.suttong.com

My Books   AMAZON

FACEBOOK   Geoff W. Sutton

TWITTER  @Geoff.W.Sutton

LinkedIN Geoffrey Sutton  PhD

Publications (many free downloads)
     
  Academia   Geoff W Sutton   (PhD)
    
  ResearchGate   Geoffrey W Sutton   (PhD)







Dark Triad Scale (Dirty Dozen)

The toxic triad is commonly known as the Dark Triad . The triad consists of three sets of personality traits representing features of...