The video resources referenced in this topic stem from three sources. The first are by an instructor not at all associated or affiliated or (thus far) even known by those of us here at Lertap Central in Western Australia. He has put together a series of YouTube videos having to do with the installation and application of Lertap 5. Quite a nice job he's done, too -- he speaks clearly and his examples are excellent. Here are links to three of his productions; once you're in one of them there may be links to more Lertap-related videos:
YouTube video TD1: Installing Lertap5
YouTube video TD2: Using Lertap 5
YouTube video TD3: Processing a survey
The remaining links on this page, immediately below, lead to some videos made at Lertap Central in 2010 (Coffs Harbour). They require the Adobe Flash Player. Your browser may inform you that it won't play one of these dynamic, totally-captivating videos until you activate Adobe Flash, something that's pretty easy to do.
What was formerly Video (1) has now been removed as it was too long, excessively boring, and obviously indicated a lack of video-making experience. Fortunately, the other videos are shorter and better and note: some of the videos have corresponding "stories/themes" -- they're straightforward webpages, without "movies". Also note that the references provided for each video are more current than the videos themselves, but the videos are still quite good demonstrations of how Lertap works.
The videos do not start at Lertap 101. That was Video(1)'s job. Now that Video(1) is gone, what we hope will serve as a good-enough basic introduction to how Lertap works is this PowerPoint show. The little HelpXplain animated slide show might be useful for Lertap beginners too, and then, how about this webpage?
If you try these videos, be patient when they start as it can sometimes take a few minutes for enough of the video to come through before it will start to play. And note, please: the URLs in these videos will often point to "lertap.curtin.edu.au" (a Curtin University internet domain). As of the year 2019, "lertap5.com" became the domain. A URL such as lertap.curtin.edu.au/lelp.htm would now be lertap5.com/lelp.htm.
(2) SMA Inggris item fixes (14 minutes)
The scene: this "story" involves adjusting the scoring of three multiple-choice items so that they have more than one correct answer. Multiple subtests are set up so that the resulting new test scores can be compared to the original ones. Also demonstrated in the story is the easiest way to exclude items from scoring.
The dataset used in the video is a carefully-developed 50-item English test from Indonesia.
The themes featured in the story may be seen here.
References: giving an item more than one correct answer involves the use of *mws control "cards". These are discussed in Chapter 3 of the manual, and also in Lelp (where you'd want to look at Example C10). Excluding an item may be accomplished in numerous ways; see Lelp. Scoring a test in multiple ways is accomplished by using multiple subtests; each subtest's *col control "card" will be the same.
The last part of the "B-Science" study, also referred to as the "Lertap tips and tricks demo", covers similar material, does not involve a video, and is more recent.
(3) Trigonometry exam demonstration (20 minutes)
This video involves a 40-item test with particularly good statistics (reliability of 0.92, and only two problematic items). Both types of quintile plots are extensively demonstrated and discussed. Well into the video, at the 14:28 mark, a discussion of the "IStats" report begins, with mention of such statistics as the "SMC", "tetrachoric correlations", "eigenvalues", and "principal components".
(4) Affective scale demonstration (16 minutes)
The scene: this "story" is based on an affective instrument with 48 Likert items (strongly disagree to strongly agree). The instrument had very low reliability when it was originally scored by a hasty graduate student. Detecting how to correct the scoring involved the use of a Lertap principal-components analysis (had the student paid attention to the wording of the original items, the p-comps analysis would have been unnecessary). The reliability of the instrument jumped to 0.90 once the new scoring procedure was in place.
The themes featured in the story may be seen here.
References: reversing the scoring of Likert items involves the use of a *pol control "card", as discussed in Chapter 6 of the manual, and also in Lelp. Lertap's support for principal components is mentioned in Lelp (where reference is also made to factor analysis); a captivating, inspiring discussion of principal components, scree plots, and their relationship to reliability, as indexed by coefficient alpha, may be found in this paper.
(5) Looking for group differences (29 minutes)
The scene: this group adventure tour uses a 50-item cognitive test from Indonesia, involving almost 17,000 high school students. The "Breakout score by groups" option is applied to see if there were differences in test performance by gender. Answering this question involves an analysis of variance, followed by a boxplot. This is followed, at the 11-minute mark, by use of "Ibreaks", the "Item responses by groups" option, used to see if there may have been response differences, by gender, on each of the 50 items. Response plots are created, more analysis of variance tables are drooled over, and then differential item functioning (DIF) methods are applied to index the extent of gender response differences, per item. (To see an example of how to create empirical DIF graphs, scroll in to just beyond the 24-minute mark.)
References: Lelp! Look to Lelp for the friendly web pages which underpin this tour. The "Breakout score by groups" option is here, and the material on "Ibreaks" is here. A truly top-flight reference, one of the hottest Lertap reference documents ever, can be had herewith.