Statistical significance considers the first and third of these concerns. The middle one, bias, cannot be detected by mathematical deductive logic: it needs detailed information on the way the sample was chosen. This is dealt with in the notes on bias.
A HEIC file is a raster image saved in the High Efficiency Image Format (HEIF), a lossy compressed format. It may contain still images, image collections, image bursts, or image sequences, along with metadata that describes each image. HEIC files may also appear as .HEIF files.
However, most image editors don't yet support Apple's flavour of the HEIF format (.HEIC files), and Windows 10 does not support it at all. So if you have HEIC files, you may want, or even need to convert them to JPEGs. The simplest way to do this is to use the free iMazing HEIC Converter app.