Face validity refers to the degree to which an assessment or test subjectively appears to measure the variable or construct that it is supposed to measure. In other words, face validity is when an assessment or test appears to do what it claims to do.
Step 2: Using an electronic detector, check that the area of wall where you plan to hang the shelves is free from hidden pipes or cables. Step 3: Place your first bracket against the wall, using a spirit level to make sure it's level. Mark the fixing-hole positions with a pencil.Step 4: Using the pencil marks, drill holes into the wall.crew the bracket into place. Step 5: Slide the shelf onto the bracket to check that it's level (use the spirit level to make sure). Once you're happy with the position of this shelf and the way it looks, slide it back off the bracket so that you can position the rest of the brackets.
1 Decide how tall you want the finished shelf unit to be and how wide. 2  Bookshelves are traditionally 12 or 16 deep; of course, you can customize to suit your needs. 3  Decide if your bookshelf will have an open or a closed back. 4  If you keep the back open, your books may lean on or touch the wall behind the bookshelf. Apply wood glue to the support blocks for the bottom shelf and set the shelf in position. 2  Drill and countersink pilot holes in the side of the bookshelf and attach the shelf with 2 wood screws. 3  If you decided to use support blocks for the center shelf as well, install it now as you did the bottom shelf.