M$: It’s not a bug, it’s a feature! [Software]

posted by Helmut Homepage – Vienna, Austria, 2019-12-17 15:00 2a02:8388:6bc2:ce80:6c4e:e4df:42f4:6510 – Posting: # 20985
Views: 292

Hi all,

known for ages. All (‼) versions of Excel round the degrees of freedom down to the nearest integer.

df <- seq(10, 11, 0.2)
q  <- 4.5
res <- data.frame(df = df, correct = pt(q, df), Excel = pt(q, floor(df)))
print(res, row.names = FALSE)

[image]  df   correct     Excel
10.0 0.9994284 0.9994284
10.2 0.9994561 0.9994284
10.4 0.9994818 0.9994284
10.6 0.9995059 0.9994284
10.8 0.9995284 0.9994284
11.0 0.9995494 0.9995494


Quoting Martin:

Never never never never use Excel. Not even for calculation of arithmetic means.


[image]

Congratulations to M$ for making a continuous function discrete. :thumb down:

I had fun comparing papers by regulators based on Luther Gwaza’s Excel-Sheet for adjusted indirect comparisons with my R-package. Satterthwaite’s degrees of freedom are practically never* integers. Remember this goody of the EMA?

Results obtained by alternative, validated statistical programs are also acceptable except spreadsheets because outputs of spreadsheets are not suitable for secondary assessment.




Cheers,
Helmut Schütz
[image]

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