How Do We Combine Many Studies Into One Answer?
Take the reading one piece at a time. For each piece: read it once, underline the sentence that says what happens, then look up any word in the list. Tap a word to see its definition.
Piece 1 of 2
Every trustworthy systematic review reports its search as a flow diagram required by PRISMA 2020. Here is a worked example with realistic teaching numbers for a cleft-timing question (the numbers are constructed for teaching; the PRISMA structure is real). Records found by database search: 842. Duplicates removed: minus 310, leaving 532 records screened by title and abstract. Excluded as not about cleft timing: minus 489, leaving 43 full-text articles assessed. Excluded for wrong design or no usable data: minus 39, leaving 4 studies included in the review. How many of those 4 have poolable data for a meta-analysis is the open question.
Piece 2 of 2
The TOPS trial team noted that an earlier systematic review of cleft-palate timing trials could not statistically combine its four trials, because the trials were too different from each other to pool into one number. Different ages, different techniques, different outcome definitions: combining them would average apples and oranges.
Reading the Research
- Skim the title and abstract first to get the gist.
- Circle the one sentence that states the main claim.
- Box the evidence the authors give for that claim.
- Mark one sentence that confuses you, and move on.
Now put it together: In one or two sentences, say what this whole reading is telling you about Mateo. Then go back to the lesson and fill in the guided notes.