claim: Bob Ross never appeared on TV.
evidence: SIGMA is an electronic verification service offered by Nielsen Media Research and is generally used for commercials , infomercials , video news releases , public service announcements , satellite media tours , and electronic press kits .. Nielsen Media Research. Nielsen Media Research. video. video. It operates by encoding the SIGMA encoder ID , date of encoding , and time of encoding in lines 20 and 22 of the video signal , which is outside of the area displayed on a normal television screen -LRB- this is similar to how closed captioning is transmitted -RRB- .. video. video. On a professional video monitor with underscan capability activated or a computer display of the entire video frame , the SIGMA data will look like small , moving white lines at the top of the frame .. video. video. Nielsen provides overnight reports of airplay in all television markets in the country .. Category  : Television technology