Author information from the last article
Regionalt kunnskapssenter for barn og unge – psykisk helse og barnevern
Institutt for psykisk helse
NTNU
Forfatterbidrag: utforming/design av statistiske analyser, tolking av data, litteratursøk, revisjon av manus og godkjenning av innsendt manus.
Stian Lydersen er dr.ing. og professor i medisinsk statistikk ved Regionalt kunnskapssenter for barn og unge – psykisk helse og barnevern (RKBU Midt-Norge) ved Institutt for psykisk helse, NTNU.
Articles by Stian Lydersen
Logistic regression with more than two categories
- Stian Lydersen
23.06.2022:
When the outcome variable has only two levels or categories, standard binary logistic regression can be used. When it has three or more, we can use other variants of logistic regression. Let us start with an example: Munthe-Kaas et al. (1) studied a possible association between frailty before a...
Paired categorical data
- Stian Lydersen
19.05.2022:
To compare proportions in two independent groups, one can use, for example, Pearson's chi-squared test. However, if the data originate from matched pairs, we must use methods that account for the dependence within the pairs. Matched pairs can originate from various situations and trial designs. The...
Crossover trials
- Stian Lydersen
02.05.2022:
Most randomised, controlled trials are conducted with parallel groups, but some treatments can be studied more effectively in a crossover trial. In a randomised trial with parallel groups, the participants are randomised either to treatment A or treatment B. In a crossover trial, each participant...
04.04.2022:
The baseline value of an outcome variable is normally a strong predictor for the value of the outcome variable at a later time. In a longitudinal randomised, controlled trial, this should be taken into account. Let us look at an example: In 2012, all inhabitants of Trondheim aged 70 to 77 years were...
Autism spectrum disorder in preschool children in Sør-Trøndelag 2016–19
- Kristin Brobakken Eig,
- Maria Brandkvist,
- Stian Lydersen,
- Anne Lise Høyland
23.03.2022:
Clinical impressions suggest an overrepresentation of autism spectrum disorder (ASD) among young children of migrant mothers and that the severity of ASD is greater in this group. This impression is supported by an official Norwegian report from 2020, where data from the Norwegian Patient Registry...
Analysis of longitudinal data
- Stian Lydersen
17.03.2022:
In some studies, the outcome variable is measured several times for the same person, for example in studies where the patients are examined at more than one follow-up time point. In this case, a statistical method for longitudinal data must be used. Let us begin with an example: in a randomised...
Multiple imputation of missing data
- Stian Lydersen
26.01.2022:
Most statistical methods of analysis require complete data sets, but in nearly all studies some values are missing. Multiple imputation can be used to handle this. Let us consider a data set where each row in the spreadsheet contains data from a study participant. It is common that some values in...
What proportion of published research findings are false?
- Stian Lydersen,
- Mette Langaas
08.12.2021:
Not all published research findings are reproducible — some because the findings are incorrect. What is the extent of the problem? A number of researchers have attempted to estimate how often published findings are false. They have used widely different approaches. Different methods The article 'Why...