Error análisis de confiabilidad

MabelZR2020

Estoy analizando el análisis de confiabilidad de una variable. Los ítems están codificados con 0 (error) y 1 (acierto), en uno de los ítems todos los participantes acertaron, por lo que JASP no me analiza ese ítem porque lo señala como error. Cómo puedo solucionarlo????

EJ

I'll ask our expert, Don.

@Don: Google translate the above text gives:

"I'm analyzing the reliability analysis of a variable. The items are coded with 0 (error) and 1 (hit), in one of the items all the participants were right, so JASP does not analyze that item because it indicates it as an error. How can I solve that????"

Cheers,

E.J.

vandenman

Unfortunately, there is no way to compute the reliability for an item with zero variance. If you try this in R, you get the following:

library(psych)
df <- data.frame(x = rnorm(10), y = rnorm(10), z = 1)
var(df$z) # no variance
[1] 0

alpha(df)
Some items ( x ) were negatively correlated with the total scale and
probably should be reversed.  
To do this, run the function again with the 'check.keys=TRUE' option
Reliability analysis   
Call: alpha(x = df)

  raw_alpha std.alpha G6(smc) average_r   S/N  ase  mean   sd median_r
     -0.55     -0.65   -0.24     -0.24 -0.39 0.86 -0.31 0.66    -0.24

 lower alpha upper     95% confidence boundaries
-2.24 -0.55 1.14

 Reliability if an item is dropped:
  raw_alpha std.alpha G6(smc) average_r S/N alpha se var.r med.r
x     -0.24     -0.24    0.06     -0.24  NA       NA -0.24 -0.24
y      0.06     -0.24      NA        NA  NA       NA  0.06 -0.24

 Item statistics
   n raw.r std.r r.cor r.drop  mean   sd
x 10  0.82  0.61   NaN  -0.24 -0.38 1.27
y 10  0.35  0.61   NaN  -0.24 -0.25 0.76
Warning messages:
1: In alpha(df) : Item = z had no variance and was deleted
2: In alpha(df) :
  Some items were negatively correlated with the total scale and probably
should be reversed.  
To do this, run the function again with the 'check.keys=TRUE' option
3: In matrix(unlist(drop.item), ncol = 10, byrow = TRUE) :
  data length [16] is not a sub-multiple or multiple of the number of columns [10]
4: In sqrt(Vtc) : NaNs produced

The first warning message is:

1: In alpha(df) : Item = z had no variance and was deleted

JASP throws an error rather than deleting the items with a warning. If you still want to do a reliability analysis on the remaining items, I'd suggest deleting items with zero variance.

MabelZR2020

OK, thank you