Epidemiologists conducted a study to examine the relationship between steps per day and individuals' weight. They enrolled 500 participants. They collected weight using a scale and steps-per-day using a pedometer. Steps-per-day were measured for 1 month. The epidemiologists also administered a survey to collect self-reported exercise. Below are statements about the data collections. For each statement, mark if that aspect of data collection would be mostly likely to have resulted in (1) random error, (2) systematic error or (3) neither.
a. The survey questionnaire did not ask if the particiapnts thought the pedometer was accurate.
b. The scale used only reported weight kilograms.
c. The batteries had to be replaced for about 10% of the pedometers; battery replacement took 2-4 hours. No steps were recorded when the battery was dead.
d. The survey questionnaire was administered on the phone or online, depending on the participants preference.
e. The pedometer was calibrated for someone who was 5'7", but participants' height ranged from 5'0" to 6'3".
f. For 3 study participants, the epidemiologist forogt to tell the participant to remove their shoes when collecting the participants' weight. All other participants removed their shoes.