Is there any reference indicating that the low number of items of a subscale of an instrument is related to unsatisfactory Alpha coefficient value?

More Forough Mortazavi's questions See All

How to do a repeated measure anova in spss with two unmatched groups?

We conducted an intervention study with three measurements of fear in three time points. Results showed that two groups were not matched for two demographic variables (education level &...

31 December 2018 4,304 3 View

How can I replace missing values in SPSS with the means of a number of items?

In the process of doing a CFA, I have to replace the missing values with the means of 11 items. I wonder if there is a solution in SPSS.

06 July 2017 4,817 0 View

What is Youden’s index (J) and its usage?

I am evaluating the validity of a test by calculating its sensitivity, specificity, PPV, and NPP. I was asked to calculate Youden’s index (J) by this...

10 November 2016 7,128 10 View

Does reverse worded items in questionnaire desighning influence its construct validity or reliability?

I ran an EFA on the 14-item scale. results showed 4 factors, with two factors consisted of positive-worded items and two factors consisted of negative-worded items. it seems that in addition to...

02 March 2016 7,467 17 View

Are yielding good fit indices enough for concluding that a structure for a scale is acceptable? Are factors correlations important?

I run a CFA on a 14-item scale. Although the fit indices are relatively good (RMSEA= 0.066 (CI [0.053, 0.078]), SRMR=0.069, Chi-square/df=2.71, P

01 February 2016 681 6 View

Is there any cut off value for Childbirth Attitudes Questionnaire which measure fear of childbirth??

The Childbirth Attitudes Questionnaire was validated in Farsi. it is recommended to use cut off value=28 for identifying fear of childbirth. I could not find any references indicating so. It is...

06 July 2015 7,285 8 View

How can we assess the ceiling effect or floor effect of a questionnaire?

Referees usually asks about the existence of ceiling effect or floor effect in the process of instrument development. I am interested to find the way I can statistically assess them.

06 July 2015 4,846 12 View

Is it essential to assess normality of items before doing factor analysis?

My questionnaire composed of 49 items. none of them are normally distributed. Is it correct to do a CFA or EFA with non- normal data?

31 December 2014 4,904 13 View

Does ceiling effect of the items of a questionnaire influence the results of Factor analysis?

The questionnaire I worked on consists of 49 items rating on a 6 point likert scale. I found that most participants chose the highest point of many items. However, the results of CFA are good? Is...

31 December 2014 8,517 8 View

Can anyone make suggestions for using the crosswise method?

I am interested in designing questions for assessing sensitive domains. I know that the Crosswise method is suitable, but I do not know how it works.

05 June 2014 5,249 4 View

How to learn more about SPSS and its Application?

I would like to learn more about SPSS and Its application especially in regards to data analysis. Please suggest me how I can learn more about it. Thank you so much.

11 August 2024 9,101 4 View

Can I base on reverse DNA sequences to perform alignment, convert to amino acids and GenBank submission?

I have reverse sequences (AB1 format), can I base on reverse DNA sequences to perform nucleotide alignment, convert nucleotides to amino acids and deposit the sequence in GenBank database?

11 August 2024 5,138 1 View

Baseline drift in HPLC? What causes this?

Hello, Why do i see this baseline drift when i compare my blank (black) to the sample (blue)? Any suggestions as to why this happened? Thank you!

11 August 2024 3,770 4 View

Text-Communication from the M1 Hand Area using BCI—and then there is Elon Musk?

Willett, Shenoy et al. (2021) have developed a brain computer interface (BCI) that used neural signal collected from the hand area of the motor cortex (area M1) of a paralyzed patient. The...

10 August 2024 7,180 0 View

Handling Missing Data and Building a Predictive Model with Incomplete Information ?

I am developing a predictive model for a water supply network that involves 20 influencing points. However, I only have historical data for 10 out of these 20 points. I would like to know how to...

10 August 2024 4,005 2 View

Has anyone applied Python in the field of textile engineering for data analysis, automation, or smart textiles?

I'm currently exploring the application of Python in textile engineering, specifically in areas like data analysis, process automation, and the development of smart textiles. I'm interested in...

10 August 2024 7,429 2 View

How can I use the cif data obtained from rietveld refinement extracted via gsas2, for microstructural analysis using ETEX software?

09 August 2024 7,718 0 View

How are iso-frequency contours plotted?

Let's say we have a standard, regular hexagonal honeycomb with a 3-arm primitive unit cell (something like the figure attached; the figure is only representative and not drawn to scale). The...

07 August 2024 1,937 1 View

How to prepare the nanoparticle treated fungal sample for Environmental SEM analysis?

A fungal strain was treated with nanoparticles. We want to do an environmental SEM analysis. So could anyone share your views on preparing the sample? Thank you.

07 August 2024 5,307 1 View

How to normalize and take the significance of the MTT OD values with 3 replicates for the same cell-line?

Hi, I have a question about normalizing the MTT OD values for doing the statistical analysis. So, if we have 3 different plates and we call them 3 different replicates, so, first we would...

07 August 2024 8,106 4 View

Ufuk Turen

It is not about the number of items. It is a display showing consistency of the responces of participant to items.

Forough Mortazavi

The formula for calculating Alpha Cronbach indicate that the number of items in a subscaleis important.

Alpha= (n-1)/n (1-(sigmaVi/ Vtest))

n = number of questions

Vi = variance of scores on each question

Vtest = total variance of overall scores (not %’s) on the entire test

Menelaos Emmanouel Sarris

Check this:

Field, A. (2009). Discovering statistics using SPSS (3rd edition). Sage publications.

Please see page 675!!!

Thank you Menelaos. I found it

Christiaan Lako

Yes, definitely.

Happy to help Forough!